Which tool to choose
There's no "best" in absolute terms: it depends on what really blocks you.
You just want the written plan, free, starting from scratch → ChatGPT. It's the most flexible tool for conversing and correcting: it understands natural language and generates plans that take into account your level, the available equipment and your preferences. Limit: no tracking, you note down sets and weights yourself.
You want the app to track progress and adapt the loads on its own → a dedicated app. Here ChatGPT doesn't reach. For those who go to the gym and are beginners, Planfit is the concrete choice: an AI planner that knows the equipment, with unlimited workouts and logging for free. You select your gym or register the equipment you have at home, and the app generates routines based on what you actually have available.
You train with bodyweight or love HIIT (high-intensity interval training) → Freeletics. Bodyweight and HIIT routines with community features; it tracks progress and adapts the workouts.
Stated goal of hypertrophy/strength with automatic progression → Dr. Muscle. An AI app for muscle mass, with personalized plans and automatic real-time progression.
The operational advice: start from ChatGPT to understand what you need, then if you find you quit for lack of tracking, switch to a dedicated app. Combining the two is the move that holds up over time.
How to do it
We'll work with ChatGPT because it's free and requires no installation. From a browser or from the app the path is identical.
Open ChatGPT (chat.openai.com or the app) and log in. The free plan has a message cap with the most powerful model within a window of a few hours: once the limit is passed, the conversation scales down to a reduced version until the count resets. To avoid wasting messages, build the first prompt well instead of proceeding with scattered questions.
Gather your data before writing. The more data you put in, the better the plan. You need age, weight, height, level (beginner/intermediate), goal, days per week, available equipment, any injuries or limitations.
Paste the complete prompt. Replace the values with yours:
Act as an expert personal trainer. Build me a personalized
weekly workout plan.
My data:
- Sex and age: man, 34 years old
- Weight and height: 82 kg, 178 cm
- Level: beginner, I've been training for about 1 month
- Goal: lose fat and tone up
- Available days: 3 a week (Monday, Wednesday, Friday)
- Time per session: 50 minutes
- Equipment: full gym (dumbbells, barbell, machines)
- Limitations: discomfort in the right knee, avoid jumps and deep lunges
Structure the 3 days for me, indicating for each exercise: name, sets,
reps, recovery time and a short technical note.
Include warm-up and cool-down. Explain in two lines the logic
of the weekly split. Don't include exercises that load the
knee in deep flexion.
- Read it and have it corrected. If an exercise doesn't convince you or you don't have a piece of equipment, write in the same chat:
Replace the deadlift with an alternative for the hamstrings
using only dumbbells.
The AI regenerates that part without redoing everything.
- Ask for the progression. Add:
Give me the rule for increasing the loads over the next 4 weeks.
Without this step you stay stuck: if you don't track the workouts, you struggle to apply progressive overload consistently.
- Save the plan. Copy it into Notes, or ask "export everything in table format" to print it. With paid ChatGPT you can use Projects to keep everything in a single folder; on the free version open a dedicated chat and go back there every week.
Feedback: a well-made plan has rest days distributed, exercises consistent with your equipment and an explicit progression. If one of these is missing, the prompt was incomplete: go back to point 2.
Concrete example
Marco, 34 years old, sedentary, wants to get back in shape but his right knee hurts on lunges. He pastes the prompt above. ChatGPT gives him back a 3-day full-body split, replacing the lunges with reduced-range leg press and leg curl, 3 sets of 12 reps and 60 seconds of recovery. Marco notices that on Friday he has a long meeting and writes: "Move the third workout to Saturday and shorten it to 35 minutes". The AI recompacts the session keeping the fundamentals and eliminating two accessory exercises. After two weeks he writes: "I completed all the sets without effort, increase the loads". He gets the indication to go up 5% on the compound lifts. Result: a plan followed for a whole month because it was tailored to his schedule and his knee, not downloaded and abandoned.
When it does NOT work (and how to fix it)
If the AI invents exercises or absurd numbers
It happens that it proposes exaggerated reps or names of nonexistent exercises. Reply in the same chat:
This exercise doesn't exist / this volume is excessive for a
beginner: correct with realistic ranges.
The AI self-corrects. To be safe, cross-check the exercise names with the videos of an app like Planfit or look up the movement before performing it under load.
If you have an injury or pain
Here the AI has a clear limit: ChatGPT generates fitness ideas, but it doesn't diagnose injuries or replace qualified guidance or medical care. The real way out isn't a better prompt, it's a professional: if an exercise causes pain, stop it immediately and have the problem assessed by a physiotherapist or a doctor before going back to training. The AI comes after, on a body already in order.
If on the free version it blocks you after a few messages
The Free plan cuts off early and limits messages, uploads and context. Fix: concentrate everything into a rich prompt (like the one above) instead of many scattered questions; when you run out of messages with the main model, continue with the reduced version, which holds up for a basic plan, or wait for the reset.
If you quit after two weeks
The weak point isn't the plan, it's the consistency. Generating a workout is only one part; staying consistent, tracking progress and organizing the sessions over time is the real challenge. Here ChatGPT alone loses steam: switch to an app with automatic tracking, where you log sets and loads and see the curve grow week after week.
A tip from someone who actually uses it
Don't trust it blindly, but don't underestimate it. The available data say two things: on technical fitness questions the AI's answers stand up to comparison with those of certified trainers, and programs mixing AI and human coaching clearly beat AI used alone. Translated: use the AI to build and adapt the plan, but if you can, have your technique checked by a professional in person at least once. It's the combination that works.
Frequently asked questions
Can I create a workout plan with AI without paying anything?
Yes. ChatGPT on the free plan generates complete plans, and several apps offer free plans: Planfit gives unlimited workouts and logging. There are also web generators where you describe your goals by voice or text, without registration.
How detailed should my prompt be?
As much as possible. The difference between a generic plan and one that's really yours lies in the data you provide: real days, precise equipment, physical limitations. A vague prompt produces a vague plan.
Do I have to register or download something to start?
With ChatGPT in a browser you only need an account. Some web generators don't even ask for that and produce a workout on the fly without signing up.
Can AI really replace a personal trainer?
No, and anyone promising it is selling you something. The AI generates plans, suggests alternatives and keeps track of the numbers, but it doesn't correct your technique while you do a movement wrong, and that's where injuries are born. Its value is accessibility: for those who are independent and disciplined it covers a good part of what an in-person trainer does, at a fraction of the cost. Use it to build and adapt the plan; for technique, keep at least one human check.