I have this theory on giving up smoking, which I have had first hand experience with in the past. It goes along the following lines:

The first 3 days are the hardest when giving up smoking. This is the time that the nicotine is still in your bloodstream, and telling you that you need another smoke. If you use nicotine replacements e.g. patches, gum, or other, rather than going “Cold Turkey”, this may stretch on for longer. During this time you may experience unexplainable aches and pains, from headaches or tooth aches, to stomach cramps and even down to your hair hurting. This is all lies the nicotine is telling you to try and make you have another ciggy.

After 3 weeks you will feel as if you never smoked. Your body will be clean, and you no longer have the need to smoke, or the feeling that you miss it. The smell of smoke is still familiar and nice, but not enough to make you want to have one, and too much smoke (e.g. a smoky bar) can, in fact, be too much. You don’t want to smoke any more.

By this time you have been off cigarettes for so long you believe you are immune. You wouldn’t mind having the odd puff with a few drinks, and start to borrow one or two off your mates when out. After a while you think you might just buy a packet for the evening, since you’re just going to borrow them anyway. You won’t smoke the whole packet. The next morning there is half a packet next to the bed, so you slip this into your pocket and start out your day. Later on in the day you have a ciggy, because you aren’t addicted anymore, and can have the odd one. Bang, you’re hooked again.