Roller skating. I'm super unathletic, but skating (including teaching to others) was listed in the profile of a girl who contacted me on a dating site, so after chatting for a bit I suggested that as our first date. She was super patient with me, I had never put on skates before that day, and was in my 30s.

We're married now, and I now also teach skating where she does on weekends, sometimes to people who have never tried it before.