What we know from lab studies is that it's never too late to break a habit. Habits are malleable throughout your entire life. But we also know that the best way to change a habit is to understand its structure - that once you tell people about the cue and the reward and you force them to recognize what those factors are in a behavior, it becomes much, much easier to change.
Charles DuhiggHowever, to modify a habit, you must decide to change it. You must consiously accept the hard work of identifying the cues and rewards that drive the habits' routines, and find alternatives. You must know you have control and be self-conscious enough to use it -- and every chapter in this book is devoted to illustrating a different aspect of why that control is real.
Charles DuhiggBut countless studies have shown that a cue and a reward, on their own, aren't enough for a new habit to last. Only when your brain starts expecting the reward--craving the endorphins or sense of accomplishment--will it become automatic to lace up your jogging shoes each morning. The cue, in addition to triggering a routine, must also trigger a craving for the reward to come.
Charles Duhigg