Workout Tracking
- Exercise selection: search + categories + recent/favorites.
- During workout: timer/rep counter, rest intervals, current exercise.
- Minimal UI during active exercise. Full screen, large text.
- Complete: summary with stats, personal records, share option.
Progress Visualization
- Charts: weight over time, volume per muscle group, frequency.
- Calendar heat map: workout frequency.
- Personal records: highlighted and celebrated.
- Before/after (optional, sensitive — never prompted unsolicited).
Data Display
- Daily summary: calories, steps, active minutes, heart rate.
- Weekly/monthly trends.
- Goals with progress rings (Apple Watch style).
- Streak counters for motivation.
Sensitivity
- Never use shame as motivation.
- Allow hiding weight/body metrics.
- Support diverse fitness goals (not just weight loss).
- Respect privacy in social features.