One of the things that causes me a lot of pain and has changed my lifestyle happened at age 17 (I think). I bashed my toe on a rail road tie at 40 mph and it causes a lot of pain if I walk much now. I used to do a lot of hiking, not so much any more. In another crash, I tore my knee open badly, yet it causes no problems at all. The spine is another thing that can cause problems that never get better, broke mine twice dirt riding. I would still dirt ride though, if I had a bike to do it on.