Things I can't do anymore:
Run. At all. Well, I can for a short distance, but my right knee will be in pain for days afterward. That's been that way for 25 years, was the first sign after I had surgery on it.
Mow the entire yard all at once. As recently as last year I could do that. It's about half an acre and I use a self-propelled walk-behind but there are a lot of hills. Now I split it into two days and I'm thinking about making it three.
Climb stairs two at a time. I remember reading that you can tell how old you are by what you take two at a time - stairs or pills. I'm in the latter category. I can still do it but then my knee complains for days.
Someone mentioned drinking a case of beer in one day. I haven't been able (or wanted) to do that for decades.
On the plus side, although I have some heart issues, they're relatively minor, at least for now. I hit the gym three or four times a week and work out for a bit over an hour. The staff has said I work hard at it and may want to slack off a bit. Kinda goes against the grain, but okay... I think.
And DW still thinks I'm the best thing that's ever going to happen to her!