How can exercise and P. E help reduce stress?

pumps up your endorphins

Explaination:

Physical activity may help bump up the production of your brain's feel-good neurotransmitters, called endorphins. Although this function is often referred to as a runner's high, any aerobic activity, such as a rousing game of tennis or a nature hike, can contribute to this same feeling

(basically doing anything that involves moving around or being active can help you forget your irritations or struggles)

true child development specifically