Wow, I'm glad some other people have gray hair around my age (22), it makes me feel better... haha. I'm starting to get silver streaks in my side-burns.. kinda of a Mr. Fantastic thing going on.
I don't really feel old unless I think about it too much (because Im not very old). I've been working within my career goals for the 4 years I ahve been going to school. I'm working for Progress Energy, who provides power for Florida and North Carolina, doing engineering work with mentors. I have not had that "crappy college job", and having a regular 40 hour week all summer (and part time during the school year) kinda gives me a preview of the next 10 years of my life... lol
When I was younger, I messed up both of my knees playing soccer and volleyball. Now they both pop and crack when they bend. I still play volleyball and soccer and do various other fun sport things. I just have to warm up a lot beforehand. Oh, and my knees hurt when it rains... which is very often in Florida

My roommate says I have OMS: Old Man Syndrome.
Despite an injury from volleyball, my shoulder never hurts, it just clicks occasionally. The kicker is my right wrist which I hurt while returning a spike (which was probably over 100 mph) when I was in the junior olympics at 16. I had taken many hits like that before, but I guess it just hit it funny and tore some tendons and cartilledge. Also, as a dumb kid I just taped it up and kept playing; probably not the best idea in retrospect.
I also managed to tear all of the soft tissue in my left foot while playing soccer (from the big toe back on the inside of the foot). That took over a year to heal! I was playing Volleyball for UCF at the time too, so I was in pain for a good deal of the time. The doctor said I wouldn't hurt it more by playing on it, but it would just hurt a lot. That was the last year I played for UCF though.. engineering just got to be too much time.
Now, I'm buying a house, my little brother is graduating highschool this year, and I still can't believe it is 2006. lol