As far as riding. For me, I've had bad knees for years. But, what I discovered a few years ago is the more riding I do, the better the knees feel. Of course weight is also bad for the knees.
A couple of years ago I went car-free. I'm off of that now, but still like the bike. I've slowed down a lot this year, but getting out riding is still protective of the knees.
The other thing. My mother has turned 80. But, she is in a small community of people 60 to 80 or so. It is sad to see them struggling with aging, and getting weaker. I'm hoping to maintain at least leg fitness for as long as possible. I should also do some upper body strengthening too.