You know you should take a break or quit when it interferes with you life severly, or you start to feel a mental addiction. You can tell if your becoming mentally dependant on marijuana, because you smoke it when your sad or depressed just to feel better, and you smoke it all the time. If you think about smoking pot all day and night, and you do it just to feel "normal", you may be addicted just a little. Also if you steal or act differently because of your habit, you may want to take a break. That's my two cents...