Making sustainable life changes is about studying yourself, not just what other people say is good for you, or what other people believe you should do.
Study yourself, your drives, your customs, your triggers, and your personal reward system. (Your personal reward system is about what makes your brain light up. Consider that these won’t all be positive things. Many of us have brains that light up on spreading guilt, shame, and pity as much as they light up from pleasure, chocolate, service, and sex).
Duhigg’s method boils down to CRR: Cue, Routine, Reward. Master this cycle and you will be able to change just about anything.
UPDATE: Duhigg gives a 15-minute TEDx talk in August 2013 on the mental activities underlying habits and decision-making; check it out.