If you're a runner, you're probably more concerned with endurance than endorphins, neurotransmitters that act similarly to morphine by relieving pain and elevating mood. Endorphins are the cause of the coveted "runner's high," a sensation generally regarded as a state of well-being and confidence—even euphoria—during otherwise grueling activity. A runner's high can permit the body to be pushed to new limits, leaving you oblivious to the muscular pain that can accompany prolonged hard work. So if you want to send your mind soaring, make sure you follow these suggestions:
Set the mood. Endorphins increase happiness, but happiness also increases endorphins. Therefore, running in a pleasurable setting can prime your brain for an endorphin surge.
Go longer. As your body is exposed to stress, it secretes endorphins to help you get through it. Insert a random long run into your training regimen, and you should get a greater high.
Go harder. Try intervals: Alternate higher and lower intensities during a run. The greater physical demands will spike the release of endorphins more than running at a steady state will.