I could quit anytime I wanted.

This is a dangerous thought because it implies that you want to continue smoking. The more you continue to believe this thought, the more you have to convince yourself that you want to smoke, and there before the harder it will be to quit.

There is a way around this one. Consider the possibility that the reason why you have not already stopped is because nicotine addiction has warped your thought processes to the point where you fail to understand the dangers. The nature of drug addictions is to corrupt minds – maybe yours has been corrected to make you underestimate how much your body is telling you to stop?

Just. One. More.

If you could really smoke just one more cigarette, and leave it at that, this would not be a dangerous thought. But this ranks with “I'm only going to try heroin once” as a bad one. The nature of nicotine addiction is that one cigarette turns into a pack, which turns into a year, which turns into a lifetime habit.

Chances are that you have said “Just one more” at at least one previous occasion, either a New Year, a birthday or after an event that made you appreciate the precariousness of the human condition. Try to recall such a time, and then try to estimate how many cigarettes that one turned into.

At least I do not drink.

Well, drinking is not necessarily great for you either, especially not physically. But falling prey to this thought is like going into a McDonald's three times a day and ordering a diet coke with your Big Mac and fries.

In some ways, the awareness that smoking is bad for you can lead to a number of compensatory behaviors such as eating better or exercising more. This does not change the basic fact that the very best thing you can do for your health is to stop smoking cigarettes.

My father smoked for fifty years and it did not kill him.

The problem with this thought is that you are not your father. You may share half of his genes, but this does not mean all that much. Another way of looking at this is that by smoking, your father loaded one chamber of a revolver, spun the barrel, put it to his head and fired – and the hammer hit an empty chamber. Does this mean that playing Russian Roulette was a wise choice?

I'm too young to get sick from smoking.

If the world were to end in five or ten years, you might not need to worry about smoking. Maybe it will; I admit that, if I were to read on the news that the Earth was to get hit by a comet and knocked into the orbit of Mars, I would probably go and buy some cigarettes.

But the world probably will not end then. Smoking may knock ten years off the end of your life, and that might be very far away. But another way to look at this is to measure your age not from birth but from death. If you are thirty years old, the choice to smoke until you die effectively makes you forty.