"Now,I'm no scientist,but I know what endorphins are. They're tiny little magical elves that swim through your blood stream and tell funny jokes to each other. When they reach your brain,you hear what they're saying and that boosts your health and happiness. "Knock Knock... Who's There?.. Little endorphin... Little endorphin who?... Little Endorphin Annie." And then the endorphins laugh and then you laugh. See? Its Science."