It seems to me that in order to be successful exercise cannot be something that one adopts to meet a specific goal (i.e. look better, fit into a piece of clothing, address a health concern). Instead people need to adopt a way of life that includes exercise.

That's why I think the "cult" aspects of CrossFit are a lot of what makes it so successful. Other examples are people that adopt yoga or martial arts as a way of life rather than just an activity.