an idea that sounds huge if true: that the amount of motivation one can exert in a day is limited
This is basically the theory that willpower (and ego) are expendable resources that get depleted over time. This was widely agreed upon in the earlier days of LessWrong (although with a fair deal of pushback and associated commentary), particularly as a result of Scott Alexander and his writings (example illustration of his book review on this topic here) on this and related topics such as akrasia and procrastination-beating (which, as you can see from the history of posts containing this tag, were really popular on LW about 12-15 years ago). This 2018 post by lionhearted explicitly mentions how discussions about akrasia were far more prevalent on the site around 2011, and Qiaochu’s comments (1, 2) give plausible explanations for why these stopped being so common.
I agree with Seth Herd below that this appears not to have survived the replication crisis. This is the major study that sparked general skepticism of the idea, with this associated article in Slate (both from 2016). That being said, I am not aware of other, more specific or recent details on this matter. Perhaps this 2021 Scott post over on ACX (which confirms that “[these willpower depletion] key results have failed to replicate, and people who know more about glucose physiology say it makes no theoretical sense”) and this 2019 question by Eli Tyre might be relevant here.
This is basically the theory that willpower (and ego) are expendable resources that get depleted over time. This was widely agreed upon in the earlier days of LessWrong (although with a fair deal of pushback and associated commentary), particularly as a result of Scott Alexander and his writings (example illustration of his book review on this topic here) on this and related topics such as akrasia and procrastination-beating (which, as you can see from the history of posts containing this tag, were really popular on LW about 12-15 years ago). This 2018 post by lionhearted explicitly mentions how discussions about akrasia were far more prevalent on the site around 2011, and Qiaochu’s comments (1, 2) give plausible explanations for why these stopped being so common.
I agree with Seth Herd below that this appears not to have survived the replication crisis. This is the major study that sparked general skepticism of the idea, with this associated article in Slate (both from 2016). That being said, I am not aware of other, more specific or recent details on this matter. Perhaps this 2021 Scott post over on ACX (which confirms that “[these willpower depletion] key results have failed to replicate, and people who know more about glucose physiology say it makes no theoretical sense”) and this 2019 question by Eli Tyre might be relevant here.