Am I Gettng Old?

Ok so here I am sparring in karate class when I go and kick with my left leg and end up pulling my hamstring. It wasn't very painful when I did it but just walking to the car afterwards I really started to feel the pain coming on. Its been a couple of days now so it feels much better, but now my knee is beginning to cause discomfort. I don't get it...I'm only 24 and I'm getting all these pains in my body. I have some people in my karate class that are quite older than me and they seem to cope well. Am I just out of shape? I think that I do a pretty good job of keeping fit but maybe I don't....

In other news....I go to the gym regularly and there are these two guys who work there selling memberships to new members. These guys are NOT in good shape. They work out and then their post workout meal is ALWAYS pizza. I dont get it... if part of your job is selling the crediblity of your gym facility and its programs to be able to get you into shape and keep you there shouldn't you live up to those standards?
My workout partner and I always get a kick out of seeing them heading to the foodcourt and having their pizza.

Song of the Post: "The New Work Out Plan" by Kanye West