" Often when we try to start a good habit and then slip up, we describe it as a failure of willpower. But sticking to a good habit is not simply a matter of willpower. You have willpower only insofar as your prefrontal cortex is paying attention and has enough serotonin to work properly. "

― Alex Korb , The Upward Spiral: Using Neuroscience to Reverse the Course of Depression, One Small Change at a Time