I am sure it must be more complicated than "not eating a cookie depletes your willpower". So if I stare at 100 cookies in the morning, all my willpower for the rest of the day will instantly evaporate?
I was half expecting the advice to be: "the only way to achieve stuff is to give in to the less important cravings. That is, you get extremely fat eating cookies, but in exchange you finish your weekend project".
Willpower for me is the exact opposite of what you were expecting. Having willpower on the simple things leads to having it on bigger things and so on.
I also think willpower is learned just and takes time just like building muscles. It takes practice and doesn't follow a linear trajectory. There is also a personal aspect that each person must find on their own to help them keep going when the ability to maintain willpower becomes tough.
I was half expecting the advice to be: "the only way to achieve stuff is to give in to the less important cravings. That is, you get extremely fat eating cookies, but in exchange you finish your weekend project".