Started in my mid 30s. I was never good at it, but I started to enjoy it, when my knee started to act up. Doctor said it was because of an old issue from a motorcycle accident and I could either have surgery with just a 50% chance of success or drop running. As I was doing (amateurish)Triathlon training at the time, I dropped running and focused on cycling and swimming. I enjoy this very much now and even get decent progress. I’m approaching mid-40s now and I hope I can do it much longer still.