I'm 61, and if I say so myself, still fairly fit and strong. I've remained pretty much at the same weight I was when I was in my late-20s.
Anyway, about a month ago, I was watching a random YouTube video on some teenager pulling off some 'parkour' stunts and was thinking to myself... "Bloody 'ell, I couldn't do any of that".
However, just to test myself, I thought I'd try a handstand against the living room wall. I'm still reasonably strong in the arms and thought I'd be able to do it.....FAILED each time!