Your body releases cortisol in response to stress, which prepares you to fight or flee. This is a useful response in our early years when the stressors were things trying to hurt, kill, or eat us.
But modern-day stressors are different — deadlines, colleagues, managers. We aren’t running or fighting these stressors, so the cortisol stays in our body keeping us in a constant state of alert. That heightened state is a big strain on the body.
Running burns off cortisol the way the body naturally intended.