willpower has a limit and as the day goes by, we use up more and more of our willpower.Making decisions about what to eat (and not eat for lunch) telling yourself you won’t have that extra cup of coffee in the afternoon, saying “no” to a friend who wants to have dinner tonight (you can’t because you are going to study Japanese)—all these things add up throughout the day, and they deplete your willpower.Finally, when you do get home and the appointed hour for your Japanese study arrives, you just cannot do it.
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