How I use AI as my own personal trainer

The gym changed my life for the better. Three years ago I was at rock bottom and seriously unhealthy, so I decided to change that by training consistently. To learn how to lift properly I worked with a personal trainer, which was totally worth it and gave me something priceless: real human coaching. But I get that a trainer is expensive and won't be available to you 24/7. That's where AI comes in, to augment (or even automate) parts of your training.

01 Track your lifts properly

For years I tracked my lifts in my phone's notes app instead of paying for an app. It's not the worst idea, but if it isn't backed up to the cloud it can easily get lost. After a while my notes got slow, and I lost months of tracking when one note became corrupted. So I used Claude Opus 5.5 to build my own lift-tracking app with one prompt. It's been a game changer for logging each session, and the progress chart shows exactly how my strength has moved, which is far more useful than scrolling through notes.

Prefer an off-the-shelf app? Hevy now has an official ChatGPT app that can build plans and analyse your training data, and community-built connectors exist for Claude. Some of Hevy's features sit behind its paid Pro plan.

Build a simple and clean gym lift-tracking web app with the following features:

Core functionality
- Allow users to select a day of the week (Monday–Sunday).
- Users can log exercises performed on each day.
- Each exercise entry should include: exercise name, weight lifted, reps completed, sets completed, and the date (recorded automatically).

Exercise management
- Include a searchable exercise library with common gym lifts.
- Allow users to create and save custom exercises if they're not in the library.
- Custom exercises should be searchable alongside predefined ones.

Progressive overload tracking
- Store historical workout data for every exercise.
- Provide an individual exercise page that displays progress over time, with a line chart.
- Let the user switch between tracking weight lifted, estimated 1RM, and total volume (weight × reps × sets).
- Display personal bests for each exercise.

User interface
- Keep the design minimal, modern and mobile-friendly.
- Dashboard should show today's workout, recently logged exercises, and quick access to
progress charts.
- Make logging workouts as fast as possible with minimal clicks.

Technical requirements
- Use a simple database to store workouts and exercises, and persist data between sessions.
- Focus on speed, simplicity and ease of use rather than advanced fitness features.
- No calorie tracking, nutrition tracking, social features or workout plans: only lift tracking and
progressive overload visualisation.

02 Build a training plan for any situation

AI is great at building a plan around your real constraints. Paste the base context block first, then add whichever scenario prompt fits. (Fill in the orange brackets).

About me: [age], [height/weight], training for [X years]. Current lifts (working sets): [squat/ bench/deadlift/OHP or equivalents]. Goal [hypertrophy / strength / fat loss / recomp /
athletic]. I can train [X] days/week for [X] minutes. Injuries or limits: [none / details]. Exercises I like or hate: [list].

03 Get feedback on your physique

AI can assess your body composition and tell you what to focus on. To test it, I uploaded a photo of someone who's textbook "skinny fat" (not me, btw!) to Claude and simply asked: "What should I do to improve my physique?" Here's what came back.

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CLAUDE'S RESPONSE

This is a pretty common starting point: not overweight, but carrying some softness around the lower belly and sides, with fairly modest muscle in the chest, shoulders and arms. The good news is this responds well to the basics.

1) Lift consistently, 3–4 times a week. A simple full-body or upper/lower program built on compound lifts: squats or leg press, bench or incline press, rows and pull-ups or pulldowns, overhead press, Romanian deadlifts. Track your weights, aim to add reps or load over time, and take most sets close to failure.

2) Give the "visual" muscles extra work. Lateral raises for shoulder width, incline pressing for upper chest, and pull- ups or pulldowns for back width make the biggest difference to how a frame looks. Add some direct arm work too.

3) Eat around maintenance, or slightly below, with high protein. At this body composition a beginner can often lose fat and build muscle at the same time (recomposition). Roughly 1.6-2.2 g of protein per kg of body weight is a good target. A crash diet would mostly make you smaller, not more defined.

4) Move more outside the gym. Walking 8-10k steps a day helps fat loss without eating into recovery.

5) Cover sleep, posture and patience. Get 7+ hours of sleep, and add some core and glute work (planks, dead bugs, hip thrusts) for posture. Expect visible change over 3-6 months of consistent effort, not weeks.

Note to get a second opinion! AI can make mistakes, so sense-check its advice with a personal

trainer, or post to r/BulkOrCut on Reddit for a human take.

04 Fix your lifting form

You can even use AI to improve your form. Upload a clear video of yourself lifting with the prompt below, and you'll get a focused rundown of what to fix and how.

You are an experienced strength coach reviewing my lifting form. I'm uploading a video (or screenshots) of a set.
About me
- Lift: [e.g. barbell back squat / deadlift / bench press]
- Weight and reps: [e.g. 100kg x 5]
- Experience level: [beginner / intermediate / advanced]
- Goal for this lift: [strength / hypertrophy / technique / rehab]
- Any pain, injuries or mobility limits: [e.g. tight hips, old left shoulder injury, none]
- Camera angle: [side / front / 45 degrees / behind]
- What feels off to me (optional): [e.g. hips shoot up first, bar drifts forward]

How to review it
1. First, tell me what you can and can't reliably judge from this angle and video quality.
Don't guess about things you can't see.
2. Break the rep into phases (setup, descent/eccentric, bottom/transition, ascent/
concentric, lockout) and note what you observe in each, with timestamps if possible.
3. List the 3 most important issues, ranked by injury risk first, then performance impact. For
each: what's happening and where in the rep, why it matters, one simple cue to think about
mid-set, and one drill or accessory exercise to fix it.
4. Tell me what I'm doing well so I don't accidentally change it.
5. Say whether this weight looks appropriate for my current technique, or whether I should
drop the load while I fix things.
6. Tell me what camera angle to film next time to check the main issue.

Rules
- Be direct, specific and brutally honest. No generic advice that would apply to anyone.
- Give me no more than 3 fixes, so I can actually focus on them.
- If anything suggests a risk of injury or pain beyond normal effort, say so plainly and suggest I see a physio or qualified coach in person.

FILM IT SO THE AI CAN ACTUALLY SEE IT

Side-on, hip height Best default angle for squats, deadlifts and bench. Use front- on to check knees caving or uneven pressing.

Whole body, whole set Keep the bar and your feet in frame from setup to lockout. Film a working set, not a warm-up.

Steady and well lit Prop the phone up rather than having someone hand-hold it, and avoid filming into a bright window.

The verdict

AI won't replace a great coach. Mine taught me things no chatbot could. But for the 99%

of the week your trainer isn't there, it's a tracker, program designer, physique reviewer

and form checker in your pocket, for the price of a subscription you might already pay

for. Use it to stay consistent, sense-check the big calls with a human, and see a

professional if something hurts.

Here is a downloadable pdf for an overview on using AI as a personal trainer, feel free to use and share this to power you, your friends, or your clients fitness journey!