In an experiment designed to research the influence of environmental cues on our behavior, two groups of participants got popcorn in a movie theater. One group got fresh popcorn. The other group got popcorn that was seven days old.
They ate the same amount.
When presented with fresh and stale popcorn in a different environment, a conference room, the two groups did not exhibit the same mindless eating.
The moral is that when you try to change habits, pay close attention to environmental cues and plan ahead, rather than trying to rely on will power alone.
More about effective ways to change habits later.
Adapted from Neal & all (2011): The pull of the past: When do Habits Persist despite conflict with Motives. In: Personality and social Psychology Bulletin, 37 (11) 1428-1439