Willpower alone cannot change our lifestyle.
1) Only 5% of our 70,000 daily thoughts are conscious and influenced by willpower. Our hunger, satiety and habits operates out of our non-conscious mental pathways.
2) Willpower can't force subconscious abilities. If it can't make our left hands write proficiently, neither can it force us to adopt a healthy lifestyle consistently.
3) Willpower should be used to correct our automatic mental pathways. Such changes reduces negative thinking about weight loss and fitness and triggers the other 4 Forces in our arsenal. (Elements of Cognitive Behaviour Therapy).
4) The food industry profits more when we buy and eat stuff that we don't need (e.g. Sugar water) in quantities that our body don't need. We blame our lack of willpower when we are all ignorant victims of a food environment hostile to unprocessed, whole foods.