I recently went out and got my 22 year old bike brought back into working condition. My idea is to ride insstead of running a couple of days a week. I am starting to get a little soreness in my left hip from running close to 4 miles a day, and it worries me. I am 44 years old, and one of my high school friends who I used to lift weight with just went through a hip replacement. Now he was a serious runner, who ran far more than I do, and did it for a lot of years, but the fact that people that I know, who are my age, are having problems like that kind of make me want to not continue to do something that might cause problems.
Of course I am still going to run, I am already planning my next 5k, but I might try to replace it with a bike ride 2 days a week to limit the wear and tear on my body. So far I am only riding my bike to work, which is about 2 miles each way. And so far, it is killing me! Definitely harder than I remember from childhood. I am sure that I will come to enjoy it after a few weeks, but so far riding to work stinks!