by roy baumeister & john teirney
The next most important lesson was that willpower requires actual energy, i.e. glucose for the brain. You make much, much better decisions and have far more self control when you aren't tired and hungry (but we knew that, didn't we!). This is the fundamental reason why diets are so damn hard.
The book gives lots and lots of tools to help you avoid decision fatigue, outsmart yourself and reach the goals you've been striving for.