[gratalis]

This is incorrect or at least incorrectly stated with respect to the word "you". I didn't start running regularly until my late 40's and I loathed nearly every step for the first year but my fitness and enjoyment levels slowly improved especially after discovering trail running. I started participating in ultra trail races after a couple years and found a wonderful community of people enjoying an activity all around me I didn't even know existed. Now, 10 years later, I'm the fittest I've ever been and far more fit than the vast majority of 25 year olds.

Am I going to win races against people half my age who are in peak fitness for their age group? No, of course not. But I can physically do far more at 57 than what I could do at 25 with respect to running. Many people can alter the course of their health trajectories at nearly any age but it requires consistent effort and often ignoring the messages of vested societal interests telling them otherwise.

[snowwrestler]

If you had followed the exact same fitness regimen when you were 25, you would have seen better results: higher speeds, more endurance, shorter recovery times, etc.

That’s why I mentioned sports: even people who have worked out their whole lives, at the top of their sports, see declines in physical performance as they age.

Congrats on getting in shape. Relative improvements in physical fitness are beneficial and possible for many people. But it doesn’t reverse aging.

[Earw0rm]

Speed and recovery? 100%. Endurance, not so much.

Recovery times are shortest in children - and become very significantly longer even at ages where maintaining muscle mass isn't too much of an issue. Maximum speed peaks with strength in your mid/late 20s & declines from there. Endurance seems to carry on increasing in to the late 30s & declines very slowly, plenty of ultrarunners, Audax cyclists and triathletes in their 40s/50s.

[gratalis]

Obviously had I started from an earlier point, I may have achieved a higher overall peak performance level but that isn't the point I was addressing. Nothing reverses entropy that we know of but that isn't the point either. The point is that saying "you can’t do at 50 what you could do at 25" is patently wrong. I point this out simply because many people have an incorrect perception of their ability to alter their fitness via lifestyle changes.