I am 53. During the fair weather months here in New York, I commute to work by bike 3-5 days a week, do 2-3 overnight bike trips per year, and take lots of leisure rides with my wife. I'm not as fast and immune from pain as I was in my 20s and 30s, but I still enjoy being on the bike more than anything else -- AND I'm in much better shape than a lot of the 20 and 30-year-olds I work with every day.

Lots of people are going to try to convince you to retire. Many have their own agendas, like justifying their own inactivity at an early age or just wanting to hang out with you more. Don't let anyone else tell you when to get off the bike. You will know when it's time.