FitYa — AI-Powered Fitness Habit App

🚀 What inspired us

We believe that fitness should be simple, accessible, and fun — not overwhelming or time-consuming. Many people struggle to stay consistent because fitness apps often require complicated setups or strict routines.

We wanted to build an app that helps users easily build daily workout habits using AI-generated personalized workout plans.
No gym. No equipment. No complicated tracking.
Just simple, personalized workouts that fit anyone's schedule.

🛠️ How we built it

• UX & UI fully designed with Bolt
  Bolt allowed us to quickly and efficiently design the entire mobile app user experience. Without Bolt, iterating on onboarding, paywall, workout flows, history screens, and achievements would have taken significantly more time.

• AI Workout Generator
  We developed a custom GPT-4-based prompt engine that generates dynamic workout programs based on the user’s fitness level, available time, and training preferences.

• Tech Stack

  • Frontend: Expo React Native (Prebuild Workflow)
  • AI Engine: Custom GPT-4 prompt system
  • Backend: Serverless cloud functions
  • Subscriptions: RevenueCat integration
  • Data: Fully offline-first architecture
  • Audio & Haptics: Expo Audio + Expo Haptics

🎯 How Bolt helped us design the experience

Bolt played a critical role in helping us design the full product experience for FitYa:

• Quickly designed and iterated the full app flow
  From onboarding, AI program generator, paywall, to workout history and achievements — Bolt allowed us to visualize and iterate rapidly.

• History & Heatmap screens
  Bolt made it extremely easy to design beautiful progress visualizations and heatmaps, which would have been very time-consuming with traditional design tools.

• Achievement & Badge system design
  Bolt allowed us to experiment with different badge layouts and motivational designs that perfectly fit FitYa's fun and habit-building vibe.

• Mobile-first by default
  Bolt’s auto-responsive layouts allowed us to preview and fine-tune mobile designs instantly.

Honestly, Bolt saved us many weeks of UI/UX development time, allowing us to fully focus on building our AI system and subscription backend.

🔍 What we learned

• Bolt dramatically accelerated mobile-first UX design.
• Simplicity in UX strongly influences long-term habit formation.
• AI personalization works incredibly well when guided by proper prompt engineering and time constraint handling.
• Paywall design directly affects subscription conversion rates.

⚠️ Challenges we faced

• Building dynamic AI prompts that adapt workout plans based on time, without defaulting to static templates.
• Designing a fully offline-first fitness app while maintaining stable data sync.
• Integrating RevenueCat subscriptions with a seamless and intuitive paywall flow.
• Ensuring AI-generated workouts properly match session duration, user level, and training frequency.

✅ Summary

FitYa is a lightweight AI-powered fitness app that helps users build daily workout habits effortlessly. Bolt played a huge role in allowing us to design and ship the full mobile app experience extremely quickly and efficiently.

Built With

• anonymous-user-auth
• bolt
• cloudflare-workers
• expo-audio
• expo-dev-client
• expo-haptics
• expo-react-native
• gpt-4
• local-storage
• nativewind
• react-navigation
• revenuecat
• serverless-functions