Pretty easy. You get to a point where you think "one smoke won't hurt". Usually when you are with friends that smoke. And one smoke doesn't hurt, neither does the next or even if you smoke an entire pack that evening. You stop for a few weeks again and at the next braai you again have a few smokes because last time you didn't have trouble stopping the next day.
And then you buy a pack on a Saturday even though you are not even with friends that smoke. Because you didn't have trouble stopping last time, see. I think you get the picture...




