The hormone released during prolonged exercise that helps elevate mood is endorphins. These neurotransmitters are linked to the brain's pleasure centers and can create feelings of happiness and euphoria, often referred to as the "runner’s high." Endorphins also function as natural painkillers, reducing the perception of pain during intense physical activity, which can encourage individuals to push through challenges. This mood-enhancing effect is one of the reasons many people engage in regular exercise as a way to improve their overall mental health.