“The Power of Habit”. Each habit is a trigger, action, and reward. Once the habit is established firmly, you can reduce or even eliminate the reward and the habit will still happen – trigger, action, trigger, action. To change the habit, you have to catch the trigger and replace it with a different action that gets a reward. You can’t just eliminate the action. That doesn’t work. The brain doesn’t deal with “not” or nothingness very well.

via reddit of all places but i really liked that.