How does regular physical activity help manage stress levels?

Regular physical activity is known to significantly help manage stress levels primarily through the promotion of the release of endorphins. These are neurotransmitters produced in the brain that act as natural painkillers and mood elevators. When engaging in physical activity, the body responds by releasing endorphins, which can lead to feelings of happiness and euphoria, often referred to as the "runner's high." This biochemical response not only enhances mood but also helps to counteract stress and anxiety.

Increased muscle strength, reduction of body fat, and improved flexibility, while beneficial for overall health, do not directly address the biochemical mechanisms that reduce stress in the same way that endorphin release does. Therefore, it is the endorphins released during exercise that most directly correlate with stress management, making it the correct choice for understanding how physical activity affects stress levels.