As I get older I realize that some of the aches and pains I get are not going to go away. You have to learn to live with them or give up the things that cause them. If I chose the latter, I'd end up an obese couch potatoe with high blood pressure, by the time I'm 45.
I was into martial arts before MTBing. I was checking out a new studio and was talking with one of the instructors during an orientation. She asked me about any health problems or injuries I might have. I told her about the problems with one of my knees and I sometimes were a brace. I wore one of those ace braces you can by in the drug stores. Alot of people wear them while running. She told me one the instructors (2nd degree black belt) also wore a knee brace and pointed him out.
So the first few classes I'm watching this guy, he seems fines. Doing the warm ups and drills just as good if not better than everyone else and he's kick'n my butt during sparring. No fancy high kicks but he's quick and accurate with what he does throw. After class we're changing in the locker room and he takes off his karate pants. He's wearing this cyborg looking metal/velcro knee brace that you get from an orthopedic surgeon (I had one for my arm before, another story, another time ).
That gave me a new insight into my little knee problem. I had always used my knee as an excuse for any shortcomings in my abilities. This guy had to have some serious problems and here he was putting me to shame. In his situation he would have been justified in saying "Me do karate, with this knee?". I just think back on this whenever I get injured and am looking for excuses to quit.
FYI- I didn't stick with the martial arts. Got one step below black belt than quit. Why? Basically I didn't want it bad enough. The mystique of the "black belt" was gone for me by then.