1) I tend to get aches at the very top of my legs
2) An arched back will no doubt catch up with me later on in life
3) RSI - Sometimes I get a burning sensation at the back of my shoulders
4) Fatigue - Lack of proper excersise, sleep, and food can bring on an awful feeling of brain fatigue
Fatigue and general well-being and happiness drop off when all I'm doing is sitting on my butt, coding/playing games and eating junk. And it hasn't been an obvious black and white thing. Its something more subtle, and happens slowly. I don't think most people realize when its happening to them. I know I didn't. But I'm very aware of it now.
It really does help you sooo much to maintain a degree of fitness( And excercise your mind in something outside of coding. ) I started Judo last year, and let me tell you. Improvements all around. When your body is fit, it just makes a better you.
I've taken a couple of extended breaks from it, and always feel worse when I'm not training. I've been out since Sept, and can definitely feel a difference now. Its like I'm reverting back into the fatigued, not-as-lively person I was.
Anyways, I'd highly recommend a few hours a week of Judo or Brazillian Jiujitsu for anyone who wants to sharpen their mind and body. I know that sounds like a bad infomercial, but it really is true :)