21 Days vs n=1

Build habits that actually stick — 21 days at a time. 21 Days Challenge is a simple and powerful habit tracker designed for real, lasting change. Pick a goal, commit for 21 days, check in daily, and watch your streak grow one day at a time. Whether you want to drink more water, read every day, exercise, meditate, or build any daily routine, 21 Days Challenge keeps you focused, motivated, and consistent. KEY FEATURES • Multiple Habit Challenges Track several habits at once including health, fitness, learning, productivity, mindfulness, and more — all from one home screen. • Streaks & Milestones Watch your streak grow daily. Reach milestones at Day 7 and Day 14, and unlock badges as you build consistency. • Daily Journal Add quick notes, moods, or reflections with each check-in. Discover patterns and understand what works best for you. • Insightful Stats View beautiful charts showing completion rates, mood trends, and overall progress. • Smart Reminders Set custom reminders for each challenge at the times that work best for you. • Private by Default Your data stays on your device. Optional cloud sync is designed with privacy in mind. HOW IT WORKS 1. Pick your challenge — choose a suggested habit or create your own 2. Check in daily — track progress with a single tap 3. Build momentum — strengthen routines through consistency BUILT FOR EVERY KIND OF GROWTH • Health & fitness — water, sleep, movement • Learning & focus — reading, studying, skill-building • Productivity — deep work, discipline, routines • Mindfulness & wellness — meditation, gratitude, journaling • Creativity — writing, drawing, creating • Personal goals — anything that matters to you Start your first 21 days today with 21 Days Challenge — your habit tracker, streak builder, and daily journal for lasting change. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Stop eyeballing trends in Apple Health. HONEST ABOUT RIGOR n=1 is for self-experimentation — unblinded, uncontrolled, sample size of one. Results screens say so in plain language. The point isn't proof; it's a structured way to see whether the thing you're trying actually moves your numbers. THE CORE LOOP • Pick a curated protocol or design your own (intervention + duration + tracked metrics) • Log adherence and optional energy / sleep quality / mood scores in a 15-second daily check-in • HealthKit data is fetched on demand: sleep, HRV, resting heart rate, weight, VO2 max, glucose, body temperature, workouts • When the protocol ends, see a baseline-vs-protocol chart per metric with the % change called out PROTOCOL LIBRARY 12 curated experiments across sleep, circadian, cardiovascular, recovery, and lifestyle — creatine, magnesium glycinate, Zone 2 cardio, morning sunlight, and more. Every protocol ships with a falsifiable hypothesis, an honest evidence summary, explicit cautions, and a difficulty rating. No fabricated effect sizes. SHARE A RESULT When a protocol ends, share a clean image card with the headline metric, supporting numbers, and a link back to the app — for your group chat, journal, or wherever you log your experiments. PRIVATE BY DEFAULT n=1 works fully offline. Your HealthKit data stays on your device — no ads, no analytics, no third-party tracking, no account required to start. n=1 is a self-experimentation tool, not medical advice. Always consult a qualified healthcare provider before starting any new health protocol.