" Anything that keeps you moving and increases your heart rate is enough to trigger nature’s reward for not giving up. There’s no objective measure of performance you must achieve, no pace or distance you need to reach, that determines whether you experience an exercise-induced euphoria. You just have to do something that is moderately difficult for you and stick with it for at least twenty minutes. That’s because the runner’s high isn’t a running high. It’s a persistence high. "

― Kelly McGonigal , The Joy of Movement: How Exercise Helps Us Find Happiness, Hope, Connection, and Courage