Running

Just how enjoyable it can be as a primary sport. I played soccer for many years and was naturally fit from that, so I'd enter the occasional cross country or road race here and there, but it was always just this thing on the side that I didn't train for or dedicate any time to. Nowadays it's my primary sport and the one I dedicate all my time and energy towards improving at. Showing more respect to it and focusing on some of the smaller details has helped me appreciate and enjoy it more.