Habits - something we do unconsciously.
Habits are formed over a period of time and often associated with triggers e.g. eating chips on a couch forms a habit and we start eating chips just because we sit on a couch.
To break a habit: remove the triggers. To continue a habit: surround yourself with triggers.
Smokers are more likely to quit while on vacation, when surrounded by unfamiliar people and things, because the familiar triggers vanish.
Students that transfer between colleges are more likely to continue running (a habit) if training place in a new college is similar to one in previous college.