90% of all chronic pain and illnesses are amplified by having high cortisol levels. Regular exercise is just one of the many lifestyle strategies that reduce cortisol levels. This idea is not new.

Nature says thou shalt keep the air, skate, swim, walk, ride, run.
When you have worn out your shoes, the strength of the sole leather has passed into the fibre of your body.
I measure your health by the number of shoes and hats and clothes you have worn out.
He is the richest man who pays the largest debt to his shoemaker.

Ralph Waldo Emerson, 1851