Here are several thoughts:
Many humans are addicted to walking. I actually can walk and do walk quite a bit. My girlfriend, who I met online, is "able-bodied". We liked each other right away but, being a Physics major, researched CP. She found out that ambulatory people with CP live more than 10 years longer than those who cannot walk.
Secondly, workers in the field in South America, as well as slaves in the Antebellum South chewed on Cocoa leaves to get threw their days. I believe that many people with CP have A LOT of electrical noise in their brains which makes getting through the day, without rest, challenging.
Sigmund Freud, the founder of Psychology, was addicted to Cocaine. Cocaine was in the original formula for Coca Cola. It Is important to note that Cocaine today is HIGHLY refined, relative to the 1890's and 1900's.