Roller skating!
I realized that even though I hadn't been in a rink since high school, all those hours way back when laid down some serious muscle memory. I failed to fall at least two dozen times, saved by reflexes I didn't realize I had until after I'd recovered.
The community for group skates is

I'm looking forward to going again because there are a whole host of things I used to be able to do when I was 17 which I want to try doing again.
(I suppose that's true of other things in my life as well as skating.)