The rationale was based on studies on the effect of meditation on the brain, and the Ego depletion model, also called the 'strength' theory of self-control, proposed by a team led by Roy Baumeister.
[11] McGonigal defines willpower as "the ability to do what you really want to do when part of you really doesn't want to do it", and says that humans experience conflicts between impulse and self-control in personal and social contexts, giving examples such as: craving for sweet foods, the urge to be sarcastic or complaining, and the desire to procrastinate.
[12]: 14 Humans have evolved adaptations to control their instincts and successfully resist impulsive drives, because living in groups requires self-control and this—McGonigal says—means taking the harder option.
[12]: 10–11 According to McGonigal, willpower failure or success can spread through a group, because humans tend to mirror the behavior of those they are socially connected with.
[12]: 34 [13] According to McGonigal, the practice of meditation is an effective way to establish the primacy of the prefrontal cortex, thus enabling a choice to do the harder thing, when that is required for attaining a long-term goal.
[12]: 234 Energy to pursue activities is less scarce than to resisting temptation, says McGonigal, suggesting that people give their brains healthy "wants" such as vegetables or a walk after lunch, so that weight loss becomes a by-product of choice.