Build a Fitness Coach with Claude

Use Claude to create personalized workout plans, meals, and groceries.

Introduction

⚡️ 30 Second Summary

Staying consistent with fitness is hard enough without having to plan every workout, meal, and grocery trip yourself.

In this project, you will use Claude to build a personal fitness coach that creates a personalized workout plan, a customized meal plan with a grocery list, and saves your plan as an interactive artifact you can track over time.

What You'll Build

You will have a conversation with Claude that acts as your personal fitness coach. Through prompt engineering and iteration, you will teach Claude about your goals, constraints, and preferences, then let it generate plans tailored specifically to you.

By the end of this project, you'll have:

  • 💪 A personalized workout plan tailored to your goals, equipment, and schedule.
  • 📊 An interactive artifact that tracks your workout progress with checkboxes.
  • 🥗 A customized meal plan that fits your budget and supports your fitness goals.
  • 🛒 An organized grocery list ready to take to the store.
  • 💎 Secret Mission: Install the Claude Chrome extension, then let Claude navigate a supermarket website and fill your cart automatically.

YouTube walkthrough

Want a complete demo of how to do this project, from start to finish? Check out our walkthrough.

Do I need to pay to do this project?

No. A free Claude account works for the main project (Steps 1-4). The secret mission uses the Claude Chrome extension, which requires a Claude Pro or Max subscription.

Not sure if this project is right for you? Check if it matches your goals

If you're up for a bit of a challenge, quiz yourself on the key concepts up ahead in this project.

Get Started with Claude

To build your personal fitness coach, all you need is Claude. Claude is an AI assistant that can hold a conversation, remember context, and generate personalized plans based on the details you give it.

In this step, you will sign in to Claude and create a dedicated project for your fitness coach.

In this step, get ready to:

  • Sign in to Claude.
  • Create a Fitness Coach project and start a conversation inside it.

Sign In to Claude

✔️ I already have a Claude account

  • Head to claude.ai in your browser.
  • Click Log In and sign in with your existing account.

ⓧ I need to create an account

  • Head to claude.ai in your browser.
  • Click Sign Up.
  • Create an account using your email, Google, or Apple account.
  • Complete the sign-up process and verify your email if prompted.
  • Confirm you can see the main chat interface.

Do I need a paid plan?

A free Claude account works for this project. If you hit usage limits, a Claude Pro plan ($20/month) gives you more messages. The secret mission at the end uses the Claude Chrome extension, which requires a Pro or Max plan.

Create a Fitness Coach Project

A Claude Project is the best way to organize your fitness coach. Projects let you pin instructions (like your fitness profile) so Claude remembers them across every conversation in the project. This means you can start new chats without losing context.

  • If the left sidebar is not visible, click the sidebar icon (top-left corner) to open it.
  • Click Projects in the left sidebar.
  • Click New Project.
  • In the Name field, type Fitness Coach.
  • In the Description field, type: Build and track my personalized workout plans, meal plans, and weekly fitness progress.
  • Click Create project.

Congratulations, you have created your Fitness Coach project!

  • Click the plus icon next to Instructions.
  • Paste the following:
You are my personal fitness coach. Help me build workout plans, meal plans, and track my progress. Ask clarifying questions when I give you incomplete information. Keep your responses encouraging but specific.
  • Click Save.

This is just a starting point for the instructions. You will come back and update them with your full fitness profile after the next step.

What are project instructions?

Project instructions are like a permanent system prompt. Every time you start a new conversation in this project, Claude reads these instructions first. This is where you tell Claude its role and any context it needs. Right now you are setting the role and tone. After you build your fitness profile in Step 2, you will save it here so Claude remembers who you are across every conversation.

You are signed in and your fitness coach project is ready. Next up, you will tell Claude who you are so it can start building personalized plans.

Build Your Fitness Profile

You are signed in to Claude and have your Fitness Coach project ready. The next thing you need to do is tell Claude who you are. A fitness coach can only give good advice if they know your goals, your body, and your constraints.

The better your prompt is, the more personalized your workout and meal plans will be. Right now, Claude knows nothing about you. How would it know whether to recommend a heavy deadlift program or a gentle mobility routine?

In this step, get ready to:

  • Send a structured fitness profile prompt to Claude.
  • Review Claude's response and confirm it understands your situation.
  • Iterate on your profile until Claude has a complete, accurate picture.

Understand What Makes a Good Fitness Prompt

Prompt engineering is the practice of giving an AI model enough context to produce useful, personalized output. A vague prompt like "give me a workout plan" forces Claude to guess everything about you. A detailed profile prompt removes that guesswork entirely.

Send Your Fitness Profile Prompt

Before you send the prompt below, replace the default values with your own details. Each value in the prompt (like Male, 25-34, 180 lbs) is a placeholder for you to customize.

  • In your Fitness Coach project, copy and send the following prompt:
You are my personal fitness coach. Here is my profile:

- Sex: [[SEX="Male"]]
- Age range: [[AGE_RANGE="25-34"]]
- Height: [[HEIGHT="5'10\""]]
- Current weight: [[CURRENT_WEIGHT="180 lbs"]]
- Activity level (sedentary, lightly active, active, very active): [[ACTIVITY_LEVEL="lightly active"]]
- Fitness goals (e.g. gain muscle, lose weight, increase mobility, train for a 5K): [[FITNESS_GOALS="gain muscle"]]
- Goal timeline: [[GOAL_TIMELINE="3 months"]]
- Problem areas or injuries (e.g. lower back pain, tight hips, or none): [[PROBLEM_AREAS="none"]]
- Available equipment (full gym, home dumbbells, bodyweight only): [[EQUIPMENT="full gym"]]
- Days per week I can work out: [[WORKOUT_DAYS="4"]]
- Weekly grocery budget: $[[GROCERY_BUDGET="75"]]
- Dietary restrictions (e.g. vegetarian, lactose intolerant, or none): [[DIETARY_RESTRICTIONS="none"]]

Based on this profile:
1. Acknowledge my goals.
2. Ask me 2-3 clarifying questions that would help you build a better workout and meal plan for me.

IMPORTANT: Do NOT create a workout plan, meal plan, or any other plan in this response. ONLY acknowledge my profile and ask clarifying questions. Wait for me to explicitly ask you to create a plan in a later message.

Why have Claude ask questions?

Asking Claude to ask you questions is a powerful prompt engineering technique. You might not think of every relevant detail upfront. Claude's questions surface gaps in your profile that would otherwise lead to generic recommendations.

Claude will acknowledge your profile and ask 2-3 clarifying questions based on your details.

Claude's response looks different from the screenshot?

That is expected. Claude may ask different questions, ask more or fewer, or phrase things differently each time. What matters is that Claude acknowledged your profile and is engaging with your details.

Claude jumped ahead and gave me a full workout plan?

That can happen. Send a message like: "Hold on, I want to make sure my profile is right before we build the plan. Here are some corrections..." Claude will adjust and wait for your go-ahead.

Iterate on Your Profile

Answer Claude's clarifying questions. You might also realize you forgot to mention an important detail. That is completely normal.

  • Answer each of Claude's questions in a follow-up message.
  • If anything in Claude's acknowledgement is missing or incorrect, correct it too.

Why iterate before moving on?

Every plan Claude generates in the next steps builds on this profile. If your profile says "gain muscle" but you actually want mobility, your entire workout plan will be off track. Fixing the profile now saves you from starting over later.

Save Your Profile to the Project Instructions

Now that your profile is finalized, save it to your project instructions so Claude remembers it across every conversation.

Instead of writing the instructions yourself, ask Claude to do it for you.

  • Send the following message:
Based on everything you know about me from this conversation, write a project instructions prompt I can save to this project. It should include my full profile and tell you how to behave as my fitness coach. I will paste it into the project instructions so you remember me in every new conversation.

Claude generates a complete instructions prompt with your profile and behavioral rules.

  • Copy the instructions prompt Claude generated. You can click the Copy button in the top-right corner of Claude's response.
  • Click the project name (Fitness Coach) in the top-left corner of the chat to navigate back to your project settings.
  • Select all the existing text in the Instructions field and replace it with the prompt Claude wrote for you.
  • Click Save.
  • Click back into your conversation from the Chats list on the project page to continue where you left off.

Why save to project instructions?

Claude only remembers what is in the current conversation. If you start a new chat next week, Claude would have no idea who you are. Project instructions get loaded into every conversation automatically, so Claude always starts with your full fitness profile, no matter how many new chats you open.

Instructions vs. files vs. memory: what goes where?

Claude Projects give you two ways to add context: instructions and files. Instructions tell Claude how to behave (its role, tone, and rules). Files are for reference material you want Claude to read (like a PDF of a workout program or a nutrition guide). For this project, your fitness profile goes in the instructions because it shapes every response Claude gives. You do not need to use files unless you want to upload external documents later.

Claude knows who you are and what you want to achieve. Your profile is saved to your project instructions so it persists across conversations. Next, you will put Claude to work generating a personalized workout plan.

Generate Your Workout Plan

You have built a complete fitness profile that Claude can reference. The next thing you need is an actual workout plan that puts that profile to work.

Claude can generate a full weekly routine in a single conversation. But will it get everything right on the first try? What if the plan does not match your schedule, or the exercises are too advanced?

That is where iteration comes in. You will generate a plan as an artifact you can track over time, refine it, and then put it to the test.

In this step, get ready to:

  • Ask Claude to generate a fitness tracker artifact with your personalized workout plan.
  • Review, adjust, and personalize your tracker design.
  • Test your tracker by asking Claude to swap an exercise.

Start a New Conversation

Your profile is saved to the project instructions, which means you can start fresh conversations and Claude will still know who you are.

  • From your Fitness Coach project page, type your next prompt in the text box at the top to start a new conversation.

Request Your Workout Plan

Now that Claude knows your fitness goals, experience level, and available equipment, copy and paste the following prompt into your conversation and press Enter to send it.

Based on the workout plan you would recommend for my profile, build a fitness tracker artifact.

Four screens via bottom nav: Dashboard, Workout, History, Progress

Dashboard: Show my current streak, this-week workout count, and total workouts as stat boxes. Quick-launch buttons for each workout day from my plan (e.g. "Day 1: Upper Body", "Day 2: Legs"). Show my top 3 personal records with weight, reps, and date.

Workout screen: Active workout logger. Show the date at the top. Start with a warmup section (5 min cardio + dynamic stretches), then list each exercise with muscle group, a table with Set number, Previous session reference, weight input, Reps input, and a tap-to-complete checkmark. Completed sets turn green. End with a cooldown section (stretches). Add Set button per exercise. Add Exercise button opens a bottom sheet picker. Live elapsed timer. Finish and Discard buttons.

History screen: List of past workouts with name, date, duration, total sets, and exercise pills. Flag any exercise that hit a PR on that session with a trophy badge.

Progress screen: Horizontal bar chart showing weekly volume broken down by muscle group. Below that, a sparkline card per exercise showing weight-over-time trend with current PR displayed prominently.

Design:
- Sports/athletic theme with a dark background and bold typography (use Barlow Condensed or similar athletic font, avoid Inter/Arial), electric blue accents, sharp card layouts
- Current weight: [[CURRENT_WEIGHT="180 lbs"]]
- Goal weight: [[GOAL_WEIGHT="170 lbs"]]
- Goal timeline from my profile displayed at the top
- Card-based layout, generous spacing, easy to read at a glance
- Fully responsive and mobile-friendly
- All inputs are inline, no modals or popups
- React with useState/useEffect only, Tailwind core utilities for styling

This is a big prompt, so Claude may take a minute to generate the artifact.

What does this prompt do?

This prompt asks Claude to build a full fitness tracker as an artifact, a standalone interactive app that lives in Claude's sidebar. The prompt specifies four screens (Dashboard, Workout, History, Progress) and a design theme so Claude builds something you can actually use day to day.

Not sure about your goal weight?

Not everyone has a specific number in mind, and that is perfectly fine. If your goal is to gain muscle, improve endurance, or increase mobility rather than lose weight, you can replace the goal weight with a different metric like "bench press 200 lbs" or "run a 5K in under 30 minutes." You can also ask Claude: "Based on my height and current weight, what would be a healthy goal weight for someone trying to gain muscle?"

✔️ Claude generated an artifact

Claude generates a fitness tracker with four screens: Dashboard, Workout, History, and Progress. The exercises, sets, and reps are based on your profile. The artifact appears in the right-hand sidebar of your Claude conversation.

  • Click the artifact in the sidebar to open it in full view.

ⓧ Something went wrong

If Claude did not generate an artifact, or the artifact is missing screens, try these fixes:

  • If Claude gave you a text response instead of an artifact, send: Please generate this as an interactive artifact, not a text response.
  • If the artifact is missing one or more screens (Dashboard, Workout, History, Progress), send: The artifact is missing the [screen name] screen. Please add it.
  • If the artifact shows an error or blank screen, send: The artifact is not rendering correctly. Please regenerate it.

Still stuck?

Get help with your error or share your error with the NextWork community!

Your tracker might have bugs, and that is okay.

Claude-generated artifacts are impressive, but they are not production apps. You might see a button that does not respond, a screen that does not load, or data that disappears when you switch tabs. This is normal. When something breaks, just tell Claude what went wrong and it will fix it. Iterating on bugs is part of the process, and it is exactly how real software gets built.

💡 What about my data?

Your tracker works within a single session, but data you log (like completed sets or weights) will not carry over when you close and reopen the artifact. Claude artifacts do not have access to localStorage or any browser storage, so there is no way to save progress between sessions right now. Think of this version as a plan viewer and single-session logger. In Part 2 of this series, we will build a version with a real backend so your data persists permanently.

Review, Adjust, and Personalize

Your first workout plan is a starting point. The real power of working with an AI agent is iteration. You do not need to get everything right in a single prompt.

  • Review the plan Claude generated. Does it match your schedule, preferences, and ability level?

✔️ I'm happy with my plan

Great! Move on to personalizing the design below.

ⓧ I want to make some changes

Send an adjustment request to Claude. Here are some examples:

I only want to work out 4 days a week, not 5.
Replace burpees with something lower impact.
Add more stretching for my hip flexors.
Can you make the Wednesday session shorter? I only have 30 minutes.
  • Pick at least one adjustment that applies to you and send it to Claude.
  • Review the updated plan that Claude generates.

Claude regenerates the workout plan with your changes applied.

Claude's suggestions do not match my fitness level?

Tell Claude directly. For example: "These exercises are too advanced for me. I am a beginner and need simpler alternatives." The more specific you are, the better Claude adapts. Need more help adjusting your plan?

This artifact is something you will come back to every day, so make it yours. Ask Claude to restyle the design until it looks the way you want.

  • Send Claude a message describing how you want the tracker to look. Here are some ideas:
Add color coding for different muscle groups.
Make it more compact so I can see the whole week without scrolling.
Add a motivational quote at the top that changes each week.
  • Review the updated artifact and keep iterating until you are happy with the design.

Test Your Tracker

Your artifact is ready. Before moving on, try it out to make sure it works the way you want.

  • Open the artifact in Claude's sidebar and tap through one of your workout days. Try logging a few sets to see how the interface feels.
  • Now ask Claude to make a live change to your plan. For example:
Swap the barbell rows in my Day 1 workout for dumbbell rows. Update the tracker so I can see the change right away.
  • Watch the artifact update in real time. This is how you will adjust your plan going forward whenever you want to try a new exercise or change your routine.

Use your phone at the gym

You can open your Fitness Coach project in the Claude mobile app and view your workout plan between sets. Your project instructions sync across devices, so Claude always knows your profile. Just keep in mind that artifact data does not sync between conversations, so use the same conversation to view your plan rather than starting a new one.

Your workout plan is locked in and tested. Next up, Claude will create a meal plan that fuels your training and fits your budget.

Generate Your Meal Plan

Your workout plan is ready. But training is only half the equation. Nutrition is what actually drives results, whether your goal is losing weight, building muscle, or simply feeling better. Claude already knows your goals, your budget, and your dietary needs from your fitness profile, so let's put all of that together into a personalized meal plan.

In this step, get ready to:

  • Ask Claude to generate a weekly meal plan.
  • Review and adjust the plan to your preferences.
  • Finalize and get an organized grocery list.

Request Your Meal Plan

Now it's time to ask Claude to build a meal plan that supports your workout routine. The key to a good prompt here is specificity: you want Claude to know exactly what to include and what constraints to respect.

  • In your Fitness Coach project, send a prompt like this:
Now create a weekly meal plan that supports my workout plan. Use the grocery budget and dietary restrictions from my profile.

Include breakfast, lunch, dinner, and one snack per day. Recommend daily calorie and protein targets based on my profile and goals, and show estimated calories and protein per meal.

Keep the meals simple and quick to prepare. Add the meal plan to my existing fitness tracker artifact, below the workout plan.
  • Press Enter and wait for Claude to generate the meal plan.

Claude adds the meal plan directly to your fitness tracker artifact. Everything lives in one place: weight tracking at the top, workout plan in the middle, and meal plan at the bottom.

Why add it to the same artifact?

Keeping your workout plan, meal plan, and weight tracker in a single artifact means you have one dashboard for your entire fitness journey. You do not need to flip between different artifacts or conversations to see the full picture. Claude already knows your budget and dietary restrictions from Step 2, so you only need to add new details like cuisine preference and prep time.

Review and Adjust

Your first meal plan is a great starting point, but it probably needs some tweaking. Read through the meal plan Claude generated.

✔️ I'm happy with my meal plan

Nice! Move on to the next section to finalize your grocery list.

ⓧ I want to make some changes

Send follow-up messages to make adjustments. Here are some examples:

I do not like salmon. Replace it with chicken or tofu.
Can you make the breakfasts faster? I only have 10 minutes in the morning.
The grocery list is over budget. Can you find cheaper alternatives?
  • Keep adjusting until you are happy with the plan.

What makes this different from a regular recipe search?

A search engine gives you individual recipes with no coordination between them. Claude builds a meal plan where each meal works together toward your weekly nutritional goals and budget. Change one meal and Claude recalculates the rest.

Finalize and Get the Grocery List

Once your meal plan looks good, ask Claude to add a grocery list to your artifact so everything is in one place.

  • Send this prompt to Claude:
Finalize this meal plan. Add a grocery list to the artifact, organized by store section (produce, dairy, meat, pantry) with quantities.
  • Open your artifact and confirm it now has all four sections: weight tracker, workout plan, meal plan, and grocery list.

Claude adds the grocery list to your artifact, organized by store section so you can shop efficiently.

Your workout and meal plans are complete. You have everything you need to start your fitness journey.

Secret mission

You have a workout plan, a meal plan, and a grocery list. That covers the planning side of your fitness journey. But there is one more thing left to do: actually buying all that food.

In this secret mission, you will install the Claude Chrome extension, then let Claude navigate a supermarket website and add items to your cart for you.

In this secret mission, get ready to:

  • Install the Claude Chrome extension.
  • Send Claude to a supermarket website to shop for your grocery list.
  • Review and finalize the cart on your desktop.

Send Claude to the Supermarket

Clean Up Your Resources

Clean Up Your Resources

Decide whether to keep your resources running, pause them to come back later, or delete them entirely.

This project has no ongoing costs if you used a free Claude account. Your conversation history is automatically saved in Claude and you can return to it anytime.

Resources you used:

  • Claude Project (Fitness Coach)
  • Claude conversation history
  • Fitness tracker artifact
  • Claude Chrome extension (secret mission only)

✔️ Keep everything running

No action needed. Your fitness coach conversation persists in Claude. You can continue chatting with it, ask for plan updates, or generate new meal plans anytime.

✋ Pause - I'll come back to this later

No action needed for this project. Claude Projects and conversations persist automatically at no cost. When you are ready to come back, open your Fitness Coach project in Claude and pick up where you left off.

ⓧ Delete - I don't want to use this again

Remove all project resources and start fresh if you ever want to rebuild.

  • Delete the fitness coach conversation in Claude if you do not want to keep it.
  • If you completed the secret mission, empty your supermarket cart and uninstall the Chrome extension.

Well Done, Coach.

Well Done, Coach.

Nice work! 🚀 You just built a personal AI fitness coach that creates custom workout plans and generates meal plans within your budget.

You've learned how to:

  • 📝 Craft a detailed prompt that gives Claude the context to act as a fitness coach.
  • 🏋️ Generate and iterate on a personalized workout plan tailored to your goals.
  • 📊 Save your plan as an artifact for tracking progress over time.
  • 🥗 Create a meal plan with a grocery list that supports your fitness goals and budget.
  • 🔄 Practice prompt engineering to refine AI outputs until they match your needs.
  • 💎 Use the Claude Chrome extension to automate grocery shopping on a real supermarket website.

Ready to quiz yourself? 💪

p.s. Does it say "Still tasks to complete!" at the bottom of the screen?

This means you still have screenshots left to upload, or questions left to answer!

  1. Press Ctrl+F (Windows) or Command+F (Mac) on your keyboard.
  2. Search for the text Return to later.
  3. Jump straight to your incomplete tasks!
  4. 🙋‍♀️ Still stuck? Ask the community!