Jaime, I believe that it is all about the mental mindset that you have. You were able to make the conscious choice to quit smoking. You were of a sound mind when you did that. Yes, you were craving it both psychologically and physically, but your mind was able to overcome those two things by using reason and logic. I think that in the case of someone who is O.C.D, their mind is compromised and even if they know it is wrong, they just don't have the mental capacity to override that part of them that causes them to keep acting in destructive ways.