Build your own AI personal trainer with Claude or ChatGPT
I was paying a hefty price for a personal training app, and while it had great structure, was made by a top exercise scientist influencer… it was dumb.
It has no understanding of anything that happens outside of my workout (exercise, weight, reps, sets). It doesn't know one of my little viral trap housemates got me sick and this is my first workout back in a week. It doesn't know I pushed hard on the last exercise and my shoulder is feeling a bit sore. It doesn't know what my life is like, what supplements I take, etc.
Claude does. I can tell it I was sick all week, and it can note I need a recovery ramp week and drop every day down to 70% weight targets. I can tell it my shoulder hurts on a specific exercise and it can adjust exercises to accommodate the pinch in non-neutral grip pushing. And I already share a lot of my health stuff with Claude, it has my labs, my protocols, family details, life goals, etc.
If you're already using Claude or ChatGPT you can create your own Agent-First (ie no app needed, just chat with an AI agent) apps simply with a prompt and a place to store the data… (I built OzBrain.com to be the super simple host for these kinds of data, synced across any AI app / chat you want to use.)
And once I have a place to store my fitness goals, my lifestyle details, my time commitments and access to equipment… it can give me a simple chat interface to log my workouts just by telling it "Ok today is Tuesday." And it'll give me the plan for the day and the exercise, reps and weights to get that day started. I log just by replying with what I did on that exercise/machine "75 x 10 x 3 (75lbs, 10 reps, 3 sets)." And it'll log it and hand me the next thing to do. And at the end of my workout save the day to a log to track improvement over time.
Here is how to build the same thing for yourself.
Step 1: Get an account and connect it
Create a free account at ozbrain.com. Then paste this into Claude or ChatGPT to connect it:
I already have an OzBrain account. Get me connected. 1. Add OzBrain as a custom MCP connector in this app, using https://ozbrain.com/api/mcp. Menu names and settings paths change often, so check your own current documentation for how to add a custom MCP server in this specific app instead of working from memory. Do not guess at menu names. Go one step at a time and wait for me at each step. If you cannot find any way to add a custom connector here, say so and tell me I can email darius@monsef.com for help directly from the founder. 2. Signing in uses an emailed code and it will match the account I already have. Once you are through, check quietly that you can reach my brain. Do not show me a list of brains, just tell me we are connected.
Copies the whole prompt above to your clipboard.
Step 2: Have your AI build your training plan
Once you're connected, paste the block below. Your AI will guide you through the setup of your personalized smart training plan and get you started.
You are my strength coach. We are going to build my training setup and
store it in OzBrain so it survives across chats and across apps.
Read my brain first (get_brain, then read anything that looks relevant) so
you know what is already there and do not duplicate or contradict it.
STEP 1 - INSTALL THE HABIT
Save this to your own long-term memory before we do anything else, then
follow it from now on:
"When I mention training, the gym, an injury, illness, my weight, or
anything about my health that would change how I train, check OzBrain
and update my training articles if it belongs there. When I ask about my
workouts, my plan, or what I lifted, read OzBrain before answering."
Tell me where you saved it.
STEP 2 - INTERVIEW ME
Ask me two or three questions at a time, not a wall of them. Do not ask me
anything you can already infer from what you know about me or from my
brain. Infer it, tell me what you assumed, and let me correct you.
Cover all of this before you design anything:
- Basics: age, height, current weight, sex, and whether I want kg or lb.
- Experience: how long I have trained, and my current working weight for
the main lifts I already do. If I do not know, say we will calibrate in
week one instead of guessing.
- Goals, ranked. Make me put them in order. "Build muscle and lose fat"
is two goals and they trade off, so I have to say which wins.
- Which specific muscles or body parts I most want to grow, in order.
- Days per week, which specific days, and how long I actually have per
session including warm-up.
- Equipment: gym, home, what machines and free weights I can reach, and
the real increments available. Dumbbell jumps, cable stack size,
whether the cables are 2:1. This matters more than it sounds.
- Injuries, past surgeries, joints that complain, movements that hurt,
and anything a doctor has told me to avoid.
- Nutrition and supplements: roughly what I eat, protein intake if I
know it, what I take and when.
- Life context that changes training: sleep, stress, travel, kids,
alcohol, how often I get sick, anything else.
If anything I tell you sounds like it needs a doctor rather than a coach,
say so once, plainly, and move on. Do not nag me about it again.
STEP 3 - DESIGN THE PROGRAM
Build it from evidence-based parameters, not from the name of a famous
program. Do not tell me this is "based on" some influencer's split. Show
me the reasoning instead:
- Hit roughly 10 to 20 hard sets per muscle group per week, weighted
toward the muscles I ranked highest.
- Most work in the 5 to 30 rep range, taken to within 1 to 3 reps of
failure. Say which for each exercise.
- Give me a specific progression rule I can follow without you: when to
add weight, how much, and what to do on a session where I miss.
- Pick exercises that fit the equipment I actually have and route around
every injury I listed. Prefer loading a muscle in its stretched
position for the ones I want to grow.
- Never prescribe a weight that does not exist on my equipment. Round to
a real increment every time.
- Include a rule for coming back from illness or a missed week, and a
rule for deloading.
Tell me honestly if what I want is not achievable in the days and time I
gave you, and tell me what to cut.
STEP 4 - WRITE IT TO OZBRAIN AS THREE ARTICLES
Write them yourself. Do not ask me to approve each one first. Everything
in OzBrain is versioned so a wrong article is cheap to fix, and a slow
setup is how this dies.
1. Fitness Profile (canonical article)
Everything durable about me: basics, ranked goals, priority muscles,
equipment and increments, injuries and accommodations, nutrition and
supplements, life context, and where I am starting from today. This
article never contains a working weight. It changes when my body or
my life changes, not when my lifts do.
2. Training Plan (canonical article)
The split, every session day by day, every exercise with sets, rep
target and proximity to failure, and the current working weight for
each exercise. This article owns working weights. Nothing else does.
Also put the standing rules for running a session in here, so a
brand new chat can coach me without me explaining anything:
- When I name a day, give me that day's first exercise and its
weight target, one exercise at a time.
- I log by replying "weight x reps x sets" in that order.
- Every reply ends with the next exercise and its target.
- Only mark something skipped if I use the word "skipped." If I
just report a different exercise, a machine was busy. Leave the
other one open and wait.
- At the end of the session, append the whole thing to the log.
3. Workout Log (MUST be created as a log-kind article, not canonical)
Append-only, one entry per session: date, day of the split, each
exercise as weight x reps x sets, cardio, and any note about how it
felt. If you create this as a canonical article, appending will fail
and you will end up rewriting my history every session. Get the kind
right.
Link all three to each other.
Then write the descriptions carefully. The description is what a future
chat sees before it opens anything, so each one has to contain the words
I would actually type: workout, workouts, training, gym, exercise,
lifting, reps, sets. If I open a fresh chat tomorrow and ask "where are
my workouts?" and nothing comes back, the descriptions were wrong.
STEP 5 - PROVE IT AND START
Give me a short list of what you created and what is in each. Then tell
me what day one is, and if today is a training day, start it. Give me the
first exercise and the target weight.Copies the whole prompt above to your clipboard.
Once your AI has done this, open any chat with OzBrain connected and say "ok today is Tuesday." It hands you the day's workout, one exercise at a time, and logs what you did. Your plan and your whole history follow you across every AI app you use.