Citing study after study (perhaps too many for an otherwise enjoyable read) Baumeister and Tierney argue willpower actually comes from the muscle of the mind and that it can be strengthened.
Just like any muscle, the brain is strengthened with rest and sleep. After you work your brain, it needs rest in order to grow. Getting enough sleep is key, and taking breaks at regular intervals will help. Ever notice how you have more willpower in the morning than in the evenings, and after a meal as opposed to when you’re hungry? More here....
-- Donald Miller
As Donald ends up noting, realizing that the brain is a muscle has helped me, too.
