It's well known that geeks, and me in particular, aren't very fond of physical exercise. Yet, many are fond of martial arts, which is arguably a form of physical exercise. I have a theory as to why this is though.
Geeks also dislike drudgery and menial tasks that don't spark the mind. Such tasks are without purpose and spiritually void, and hackers feel that they're wasting their own time and talent, as well as that of others, by doing menial tasks when they shouldn't have to. Putting these two together, we realize that most kinds of workout are in fact exactly this: menial tasks without further purpose. It's pure drudgery, and we thus detest it.
So why do we do martial arts? Because martial arts are not about physical exercise; they are about learning how to control your own body, how to fight, and in some cases how to reach "inner balance". The physical exercise is just a side effect of that. This does in fact go for other things too; DDR springs to mind. So in other words, geeks don't have a problem with exercising; they have a problem with doing mindless, menial exercise with no further point.