I suppose there are more reasons to it than just getting in shape. I live in a building with A LOT of senior citizens (welcome to South Florida) and many of them live alone. I think some of them may be going for companionship. Getting old and losing the people dear to you cannot be easy. There's a lady on my floor who has a walker and she just walks up and down the hall and goes down the elevator to get her mail and stretch her legs. I'm not sure how old she is, but she's small, frail and hunched over. So to me, it's seems like too much damage has been done and I think it's great that she does laps in our hall. She has a little transistor radio attached to it that she listens to so you can hear her coming and going.
There's also an older woman who lives here who leads a Tuesday night yoga class and an every other day water aerobics in the community pool and I've been around when these classes are going on and really it's a great excuse for the building's residents to get together and gossip.
Everybody's story is different. Maybe those older people who aren't lifting the heavy weights have a reason why. Or maybe they've just gotten to the age where they just don't really give a F what anyone thinks.
But yeah, at age 42, I want to be able to lift heavy stuff for as long as I physically can.
Just keep in mind what is in your signature.