h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The reason football (as in the game where the foot comes into contact with the ball, not one where you spend more time putting on your armo(u)r and watching adverts) players run around so much when they score is because scoring a goal is the most exhilarating experience (second to sex, as most players will agree).
The beauty of football is the fact that so few goals are scored. Of course in games such as Gridiron or Basketball, or even our own bastardization Rugby, so many "scores" are made that no-one is going to celebrate them that much. In football, after 89 minutes of deadlock, someone sticks one in the back of the net to secure a vital win and, surprise surprise, the whole place goes wild.