The specifics are disputed, but we needn't be so specific for the advise to hold.
> But that story is about to change. A paper now in press, and due to publish next month in the journal Perspectives on Psychological Science, describes a massive effort to reproduce the main effect that underlies this work. Comprising more than 2,000 subjects tested at two-dozen different labs on several continents, the study found exactly nothing. A zero-effect for ego depletion: No sign that the human will works as it’s been described, or that these hundreds of studies amount to very much at all.
The mind is a wacky thing, I think we know a lot less about it than we believe. One idea I like which seems to have some real world support is that your mental models make all the difference -- if you believe that something's hard and unpleasant, your belief becomes a self-fulfilling prophecy and you'll experience distress when you do it. If you're able to somehow reshape your beliefs, that distress may diminish. Cognitive behavioral therapy is based on this model and has a strong clinical track record.
> If ego depletion does turn out to be wrong, it’s striking how seemingly well-established it became before more rigorous investigations dispelled the assumptions it rests on. The story of its rise and fall also shows how faulty assumptions about willpower are not just misleading, but can be harmful. Related studies have shown that beliefs about willpower strongly influence self-control: Research subjects who believe in ego depletion (that willpower is a limited resource) show diminishing self-control over the course of an experiment, while people who don’t believe in ego depletion are steady throughout. What’s more, when subjects are manipulated into believing in ego depletion through subtly biased questionnaires at the outset of a study, their performance suffers as well.
https://getpocket.com/explore/item/against-willpower
EDIT: It appears the studies are cited at the bottom of the article.
If a group of teenagers were taught that every time they exercise their willpower it becomes stronger, in a very immediate sense, would we see their self control actual improve over the course of day.
