I recently stopped smoking and as a result feel better than I have in a long time. I have more energy, feel healthier, and don't have the guilt that accompanies lighting up.
I read a book called "The Nicotine Trick" a few months back and gave stopping a shot, it didn't work as I don't believe I was ready to give up. However, 3 weeks ago I decided I'd had enough, and I'm now a non-smoker.
According to the book, the mistake arises not when you smoke your first cigarette, but when you smoke your second. The second cigarette you smoke (assuming it's within a 4 day period) effectively cures the anxiety that accompanies the nicotine withdrawl. The withdrawl being a result of smoking that first cigarettem with nicotine withdrawl occuring roughly an hour after consuming nicotine. The second cigarette then, by curing the withdrawl, is then perceived as pleasurable, just as is smoking in general. There's also a self-justification aspect whereby inevitably smokers question why they are indulging in something they know will kill them, and the logical inference they make will be that it is pleasurable.
Quitting smoking is one of the hardest things I've done, though a recent lifestyle change made it somewhat easier. I think non-smokers would do well to give a little more understanding to smokers, and try not to judge too harshly for no one is perfect.
Nicotine addiction is also possible through smoking class c drugs and this is how I personally got hooked. Most people who indulge in this don't realise that nicotine addiction will probably be a result, and usually occurs pretty quickly whether they realise it or not, nicotine is after all more addictive than Heroin.