We Built the Personal Trainer That Should Have Always Existed

You’ve downloaded the fitness apps. You’ve tried the 12-week programs from Instagram. Maybe you even hired a trainer for a few months before the cost became unsustainable. And yet here you are, still searching for the thing that actually works for your life.

We know the feeling. That’s why we built SensAI.

SensAI is an AI personal trainer that combines your real health data from your Apple Watch and other wearables with the intelligence of large language models to create coaching that’s genuinely personal. Not “pick your goal and we’ll slot you into a template” personal. Personal like a coach who knows your sleep was terrible last night, that your left shoulder has been bothering you, and that you only have 35 minutes before your next meeting.

This is the product we wish existed when we started training. So we built it.

The Problem Nobody Has Solved

The fitness industry has a personalization problem, and it’s worse than most people realize.

Generic training programs take millions of unique humans and sort them into maybe three buckets: beginner, intermediate, advanced. Pick your goal, get your PDF. The program doesn’t know that you slept four hours, that you’re recovering from a cold, or that you haven’t squatted in three weeks because your knee was acting up. It doesn’t care. It’s a spreadsheet with pictures.

Human trainers are better, but they come with hard constraints. A good one costs $150-250 per session. Train twice a week and you’re spending $1,200-2,000 a month. Even then, your trainer sees you for two hours out of 168 in a week. They’re guessing about the other 166.

Then there’s the new wave of “AI-powered” fitness apps. Most of them are databases wearing a trench coat. They have a library of pre-built workouts and some if-then logic to swap exercises around. That’s not intelligence. That’s a search filter with good marketing.

The core issue is simple: nobody is accounting for your actual life. Your recovery. Your stress. Your constraints. The things that change daily and make the difference between a productive workout and one that sets you back.

What We Built

We started with a question: what if your training program was rebuilt every week by a coach who had access to everything a human trainer would want to know, and could process it all instantly?

SensAI combines two things that haven’t been brought together before: your personal health data context and the reasoning power of large language models. Your wearable data gives us the “what’s happening with your body right now” picture. The LLM gives us the intelligence to interpret that picture and act on it.

The result isn’t “personalized” the way Netflix recommendations are personalized. It’s personal the way a great coach is personal, someone who knows your history, respects your constraints, and makes smart calls on your behalf.

How It Actually Works

Your Body Talks. We Listen.

Connect your Apple Watch, and SensAI starts understanding you. Heart rate variability, resting heart rate, sleep duration and quality, VO2 Max trends, active energy. This data isn’t sitting in a dashboard for you to interpret. It feeds directly into every decision the AI makes about your training.

Had a rough night of sleep? Your AI coach sees your HRV dip and adjusts today’s session, maybe pulling back on volume or swapping heavy squats for a recovery-focused workout. Your readiness data isn’t a nice-to-have. It’s the foundation.

Talk to Your Coach

SensAI isn’t a menu you tap through. It’s a conversation. Ask it to modify your workout mid-session. Tell it your shoulder feels off. Send a photo of your form and get feedback. Ask why it programmed Romanian deadlifts instead of conventional pulls this week.

This is what LLMs make possible. Not a chatbot reciting FAQ answers, but an AI that understands context, remembers your history, and can reason about your training the way a knowledgeable coach would.

Plans Built for You, Not From a Template

Every workout SensAI generates is created from scratch for you. Not pulled from a library. Not a template with your name on it. The AI considers your goals, your equipment, your training history, your current recovery status, and your schedule to build something that makes sense for today.

We also separate what was planned from what was performed. Skipped an exercise? Cut a set short? That data matters. SensAI tracks the gap between intention and execution and uses it to make better decisions next week.

Your Program Evolves Weekly

Static programs break down after week two. Life happens. You miss sessions, you get sick, work gets crazy. Most programs don’t care. They just keep marching forward, and you either keep up or feel like you failed.

SensAI regenerates your program every week. It looks at what you actually did, how you recovered, what your wearable data says about your readiness, and what you told it in conversation. Then it builds the next week accordingly. Missed three sessions? It doesn’t just reschedule them. It recalculates volume and intensity based on where you actually are.

It Remembers Everything

Tell SensAI you have a bad back. It remembers. Mention you hate burpees. Noted. Say you can only train Monday, Wednesday, and Saturday because of your kids’ schedules. That’s locked in.

This memory system means you never have to re-explain yourself. Every conversation builds on the last one. Over weeks and months, your AI coach develops a deep understanding of who you are as an athlete, not just your numbers, but your preferences, your constraints, and your history.

Smart Guardrails, Not Guesswork

It would be easy to build an AI that just tells you what you want to hear. More volume, heavier weights, train every day. We didn’t do that.

SensAI has evidence-based guardrails built into its reasoning. Volume limits based on training age. Progressive overload rules that prevent reckless jumps in intensity. Recovery recommendations adjusted for age and training history. The AI is programmed to keep you healthy, not just busy.

Under the Hood

SensAI is powered by large language models, the same class of technology behind ChatGPT and Claude. This is fundamentally different from traditional fitness apps that use rule-based logic or basic machine learning algorithms. LLMs can reason about complex, interrelated factors the way a human coach does, but with perfect recall and infinite patience¹.

Your privacy matters to us. Health data stays on your device. When we generate plans and coaching responses, we use anonymized context, never raw personal health records. We don’t sell data. We don’t share it. Full stop².

SensAI integrates with the Apple HealthKit ecosystem, which means data from your Apple Watch, Garmin, Oura Ring, WHOOP, and other compatible devices all flows into your coaching experience³.

Who SensAI Is For

SensAI is built for people who take their training seriously but don’t have the time, money, or access for a dedicated human coach.

You might be a busy professional who needs a program that adapts when meetings eat into gym time. An intermediate lifter who’s past the beginner gains and needs smarter programming to keep progressing. Someone who owns a $400 wearable and is tired of checking their HRV score without knowing what to actually do about it.

We’re early. We’ll be honest about that. SensAI is growing and improving every week, and there are features we’re still building. But the core experience, an AI coach that knows your body, adapts to your life, and programs your training with real intelligence, is here and working today.

Try It

SensAI is free to download with a free tier that lets you experience the core product. No credit card required. No 7-day trial that auto-charges you.

Download SensAI on the App Store

We’re a small team building something we believe in, and we read every piece of feedback we receive. If you try SensAI and have thoughts, good or bad, we want to hear them.

We built the personal trainer that should have always existed. We think you’ll feel the difference.

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References

Footnotes

1. Anthropic. “Claude 3 Model Card.” Anthropic Research, 2024. https://www.anthropic.com/claude ↩

2. Apple. “HealthKit Framework Documentation.” Apple Developer, 2024. https://developer.apple.com/documentation/healthkit ↩

3. Apple. “Health and Fitness Accessories.” Apple, 2024. https://www.apple.com/shop/accessories/apple-watch/health-fitness ↩