Endorphins

Ever go for a long jog and get the "runner's high"? Well, I never have either, but supposedly once a person runs for a certain amount of time, their body begins to release endorphins, the body's natural morphine-like pain killers. Endorphins help us deal with pain as well as producing a pleasurable sensation. In fact, it has been suggested that some people become avid runners in order to obtain the pleasure produced by their endorphins.