This is one of the many self-control undermining processes discussed in the book 'The Willpower Instinct' of Kelly McGonigal. Recently, it has been translated into Dutch ('De kracht van wilskracht - Hoe zelfbeheersing werkt en wat je eraan kan doen').
Willpower is one of the hottest topics in research and studied in a diverse range of fields. This book clearly explains the science behind willpower, how it functions and what key problems are. Moreover, informed by numerous studies, the author offers useful strategies to deal with tempation in daily life. After reading this book, it is obvious that willpower is much more than a simple 'just do it' strength that you need to finish your 'to do'-list or drop a few pounds of overweight.
What I particularly like are the chapters about the role of dopamine in anticipation of rewards. When you expect, see or eat food, the brain releases dopamine and gets excited. You can override this automatic system by using your prefrontal cortex in the front of your brain, which is responsibe for more reflective and conscious decisions. Indeed, that is where willpower is located in your head. Unfortunately, this cortex has many things to worry about and gets easily distracted. Small changes or new habits that make you remind your goals and create awarenes such as meditating and exercising will build the foundation for more enduring change. They make your willpower system more efficient and fuelled to do its tasks.
This book is definitely a must-read, also because willpower is not presented as a miracle solution to life's challenges. Yes, you can get more of it, but it has its limits. That reminds me of a sentence I read in a paper of Hofmann, Friese and Wiers (2008): 'Human life would be less pleasurable without our propensity to act impulsively: An over-controlled life can be even psychologically and physically damaging.' So, train your willpower, but give yourself the occasional break.