Whether it is a dull ache from hard work or the sharp needles of a wrong move, pain is good. This is the mentality of those who have been through, among other things, football (American or European), rock climbing, amateur wrestling, long-distance hiking, and many other extreme sports.
Pain is the warning that something is wrong. The need to be above this, due to athletic or other reasons, takes discipline and courage. One such pain I know well is suffering for others: donating blood. One must relax their body, calm the mind and ignore the (slight) pain, reminding onesself that it is for a greater good. Overcoming the animal inside to bring onesself closer to being truly human.
Of course, upon receiving an injury, the body produces a wonderful coctail of chemicals, especially adrenalin and endorphins. Runner's high is a result from this, and other sports have similar names for it. When participating in a sport in which you can be removed from play because of injury, it is feared and suffering a bit of pain tends to be the norm. Very often a sports trainer spends more of the time getting the player to admit the pain (and perhaps weakness?).
There's a rush behind the fact that you're being injured, and even more so if you're dishing it out too (a natural reaction to pain is wishing to inflict it upon something, hopefully the source of the pain). The kind of power trip that goes along the lines of "I may be getting hit, but by God, I'm taking you down with me" along with the associated (typically male) psychotic feelings. You know you've seen the look: the "I'm a space marine and am going to take out the Alien Hive with my plasma pistol and a couple hand grenades" look with eyes glazed while slapping a clip in the pistol.
As I walk throught the valley of death, I shall fear no evil
For I am the meanest motherfucker in the valley. | 
