Name: VO₂ Countdown
Author: SergeyDolgov

This watch face counts down the days remaining until your target age — and the number isn't fixed. Your VO₂ max and resting heart rate are each compared to the average for your age and sex, combined in mortality-risk terms, and turned into days added or lost. Fitter than your peers pushes the count up (shown in green); less fit pulls it down (red). Raise your VO₂ max, and watch your countdown grow.
Across the top, a life bar fills from the left with the years you've already lived, leaving the years ahead on the right — so you can see life passing at a glance.
The face also shows the date, current heart rate, steps, a stress trend, battery, and a large, easy-to-read clock. In the app you set your birth date and projected lifespan, and choose accent colors for the countdown and the clock.
It's a motivational estimate, grounded in the well-established link between cardiorespiratory fitness and longevity — not a medical or actuarial prediction of your lifespan.