Not much that I can think of that I can't do that I did at that age. This is always a touchy subject with my wife and I. She is always saying we're old. I hate that. As far as I'm concerned, you're only old if you tell yourself that.
I play hoops and while I'm not as quick as I used to be, I am better in other ways. My experience counts for a lot (you will have a hard time getting a backdoor, alley oop, etc. against me). And there is at least one aspect of my game that has improved. I shoot the ball a lot better now and have more offensive skills overall than I did 20 years ago. And even despite being not as quick, I'm still fairly quick and I get lots of rebounds and loose balls. I play against guys 20 years younger and sometimes they just can't believe what an old, fat guy like me can do.
I do that because I love hoops. And I figure a day will come when my body won't let me do that any longer. So why not let it all out and have fun?
Now ask me about a treadmill and I'll tell you to go to Hell.
I still like to play football (just did yesterday, actually), too. I can't run as fast and make quick cuts, but I still have fun doing it. I just don't do this sport very often because its so hard to get enough guys together to play a good game of football. The one huge difference here is that I won't play tackle nowadays. That is because I can't afford to get injured. When I was 19, I didn't care.
I still like to ride a bike but I haven't done that much in the last couple years or so. But I can ride a bike just as well now as I did 20 years ago. Maybe that's because I used to practically live on my bike when I was a youth. You never really lose that skill.
I can't keep up with these kids on games like Call Of Duty because their reflexes seem to be quicker. I don't know if that's because I'm getting older or that they play those games night and day.
Still, I can look at the positive. I have gained a lot of other things in those 20 years. I can do things now that I never thought possible back then. Things like home repairs/remodeling/building, mechanical repairs, plan a trip and have the $$ to do it, etc.