Welcome to reThrive. We help you understand how you're aging biologically, and what to do about it, so you can live longer and healthier.

Join us on a mission to add a million years back to our lives. Check our current progress in the Circles section of the app.

What reThrive measures

Most health apps tell you what you did yesterday. reThrive tells you what it means for your longevity.

True Age

Your biological age based on four biomarkers: VO2max, resting heart rate, heart rate variability, and lean body mass index.

If you're 45 but your cardiovascular fitness, heart metrics, and muscle mass match those of a typical 40-year-old, your True Age is 40.

Pace of Aging

Whether your True Age is improving, declining, or holding steady over time.

A Pace of 1.0x means you're aging at the same rate as the calendar. Below 1.0x means you're rejuvenating. Above 1.0x is your signal to course-correct.

Getting started

1. Connect Apple Health

reThrive works with any device that syncs to Apple Health - Apple Watch, Oura, Garmin, Fitbit, Whoop, and more.

During onboarding, you'll be prompted to connect Apple Health. Grant all requested permissions so reThrive can access your heart rate, activity, sleep, and body composition data.

See the full guide: Connect your health data

2. Gather your baseline data

reThrive needs consistent data from your wearable to calculate your metrics:

For True Age (available with a minimum of 1 week of historical data):

• Resting heart rate: 4+ readings per week
• Heart rate variability: 4+ readings per week
• VO2max: 1+ reading per week
• Lean body mass index: 1+ lean body mass reading per week (or fallback with Weight and Body Fat % readings)

For Pace of Aging (available after 4 weeks):

• At least 4 weeks of True Age data

If you already have historical data in Apple Health, you may see your True Age immediately (with confidence improving as you gather more data). If you're starting fresh, wear your device consistently for at least a week.

3. Check your results and progress

Your Home screen shows your current True Age, Pace of Aging, and data completion status for the week ahead.

Your Age tab shows historical trends so you can see how your biomarkers are changing over time.

Next steps

• New to reThrive? Start by Connect your health data to get your first metrics.
• Want to understand the science? Read Key concepts: True Age, Pace of Aging, and Thrive Levers to learn how the biomarkers work and what drives improvement.
• Need help navigating? See Navigating the app for a walkthrough of each section.

Updated on: 24/10/2025