Don't know about old, but 49 here and things aren't what they used to be.
I got seriously back into exercising during the pandemic, first running and then cycling (my obsessive passion as a teen and twentysomething -- was a racer then). Initially it was to lose some weight I'd gained moving to NY and eating/drinking too many meals out. Now it's kind of its own other thing. Soreness feels different now and recovery has taken more primacy.
Needless to say I go to the gym and lift weights, where a lot of teens and twentysomethings work out. They're often calling me "sir" and holding the door -- guess I look old to them!
fogies-in-training, love it! 😂