“However, when a group of psychology PhD candidates at Case Western—including one named Mark Muraven—discovered those studies in the mid-nineties, they started asking questions the previous research didn’t seem to answer. To Muraven, this model of willpower-as-skill wasn’t a satisfying explanation. A skill, after all, is something that remains constant from day to day. If you have the skill to make an omelet on Wednesday, you’ll still know how to make it on Friday. In Muraven’s experience, though, it felt like he forgot how to exert willpower all the time. Some evenings he would come home from work and have no problem going for a jog. Other days, he couldn’t do anything besides lie on the couch and watch television. It was as if his brain—or, at least, that part of his brain responsible for making him exercise—had forgotten how to summon the willpower to push him out the door. Some days, he ate healthily. Other days, when he was tired, he raided the vending machines and stuffed himself with candy and chips. If willpower is a skill, Muraven wondered, then why doesn’t it remain constant from day to day?”
―
Charles Duhigg,
The Power of Habit: Why We Do What We Do in Life and Business
