Apparently, a craving for a smoke lasts between two and three minutes.
I read this a while ago and decided I needed distraction for those minutes while the clock was ticking and my mind was urging me to strike up.
I wrote a list (I am a list person) of things I enjoyed doing that I could do when the cravings hit me. Potter around cleaning my motorbike, make a drink, eat a piece of fruit or yogurt, etc, etc. If I had a gun, I could shoot someone I dont particularly like.
Each time a craving came upon me, distraction was the key to getting through it.