From an article. Ah, how true:

“Habits are formed when the memory associates specific actions with specific places or moods,” said Dr. Wood, a professor of psychology and neuroscience at Duke. “If you regularly eat chips while sitting on the couch, after a while, seeing the couch will automatically prompt you to reach for the Doritos. These associations are sometimes so strong that you have to replace the couch with a wooden chair for a diet to succeed.” 

Andy and I knows exactly what this means. Take last night for an example: 6pm martini + ordering delivery from Art of Pizza + couch = watch a DVD. In this case, Space: 1999.