After ~70 your body enters physiological free fall — and there are no catch-up contributions.I built a free calculator that reverse-engineers the exact fitness "minimum balance" you need today to stay independent (and ideally robust) at 90, using Peter Attia's Centenarian Decathlon framework + real longitudinal decline data. You enter your age, height, weight, and current numbers (VO₂ max, grip strength, farmer's carry, sitting-rising test score).