We may scratch our heads and wonder how this is possible, but it’s something few of us are immune to. Just think of your own biggest “I won’t” power challenge. Chances are this is something you believe makes you happy — or would make you happy, if you could just get enough of it. But a careful analysis of the experience and its consequences often reveals the opposite. At best, giving in takes away the anxiety that the promise of reward produces to make you want it more. But ultimately, you’re left frustrated, unsatisfied, disappointed, ashamed, tired, sick, or simply no happier than when you started. There is growing evidence that when people pay close attention to the experience of their false rewards, the magical spell wears off. If you force your brain to reconcile what it expects from a reward — happiness, bliss, satisfaction, an end to sadness or stress — with what it actually experiences, your brain will eventually adjust its expectations.
— The Willpower Instinct (Kelly McGonigal), Loc. 1954–60