One of the things I have noticed many people do when giving up smoking is to count the amount of time they have 'done without'. It's as though they have decided to part with a dear-old friend, counting the passage of time until they feel sufficiently distanced to no longer worry too much about the severed relationship.
Let's face it, cigarettes are our friends while we smoke. They will always be there for us in time of need. We know they are harmful and expensive, but they never let us down. In a way we hate them, because of the addiction. We know that they control us, but at least they help us too. So long as they are around, we can handle just about any situation. They are our "frienemies".
When we give up smoking, we have a hard time letting go of the "friend" part of the relationship. We tend to focus less on losing the "enemy".
Logically, one tends to think more about time lapses from when they last saw a friend than how much time has passed since they last saw an "enemy" (or at least someone they don't care about). Generally speaking, one doesn't keep track of things that are of little interest.
So, after that long-winded explanation, the key (or tip) to stopping smoking is to stop thinking of cigarettes as our "friends" and either think of them as our enemies or at least try to be indifferent to them.