On Your Bike
When I discovered fitness in my early twenties, cycling was one of the first things I took up. I think, in order, it was jogging first, then cycling, then swimming (including learning to swim for the first time), weights, and then martial arts. I'm not sure if dancing counts. The one really big thing I wanted to learn back then but didn't, and would still love to if my health ever improves enough, is being able to ride waves standing up on a surfboard.