Excerpt:
Here’s what I mean when I say there’s no such thing as willpower, despite having just defined it. Paraphrasing Laplace, I can explain all behavior simply in terms of responding to incentives. You want this whole pie in your body right now, and also you want to be two sizes smaller by next summer. Conflicting preferences are normally no big deal. You just, y’know, weigh them, make your tradeoffs, and reach a decision. But when the preferences apply at different timescales (pie now, thinner later) humans suffer from a massive irrationality which philosophers call akrasia and economists call dynamic inconsistency and normal people call … being stupidly short-sighted, or in the case of time management: procrastination.
Commitment devices are a way to change your own incentives so that willpower is a non-issue. They make your short-term and long-term incentives line up. There are many less drastic things you can do as well.
PS: Also the whole "willpower is like a muscle" theory, known as Ego Depletion, failed to replicate.