I don't know OF, I think that at some point it becomes a habit ... a lot of positive thought gurus say that 21 days sets a habit...I think there are things where this doesn't apply as much, addictions and such. But if you want to make the change then 21 days is a dang good start towards that change ... I also think that if you are trying to get rid of a bad habit, you have to replace it with something else ... if you just say I'm not going to "X", it usually works so much better if you also say ... but I will do "Y" everytime I want to do "X".