I stopped smoking in 2009, went cold turkey, stopped with no real problems despite having puffed away quite enthusiastically for over 20 years.
It was about 2 or 3 years later that I first heard about 'the Allen Carr method', and upon investigation I realised that I had kinda come to exactly the same conclusions as Carr about smoking, and I think that's why I found it relatively simple to quit.
In short, I got to the point where smoking was making me quite physically ill on a regular basis. Breathlessness, Bronchal fits, that sort of thing. It got so bad that I realised I hated smoking, and that I wanted to quit more than I wanted to continue to stop. That desire to quit gave me all the willpower required.
If often said since that I think the problem many smokers have, is that they say things like 'I should quit', 'I want to quit', 'I wish I could quit', etc, when all of those are dramatically different from 'I am quitting'. If your desire to smoke outweighs your desire to quit, then you'll just continue to smoke and any noise about quitting is just for show really.
The way to do it is do it at a point when you are absolutely convinced you want to stop more than you want to continue, then as soon as you do stop, you have to regard yourself as an 'ex-smoker', and not just a smoker who is trying to quit. Any pangs and cravings you feel is therefore just your body returning to normal, and not your body telling you you should be smoking. The 'ex smoker' mindset also helps the more bloody minded, in that when I was still getting cravings two weeks after my final cigarette, I was thinking to myself 'absolutely no way am I chucking away two full weeks of being a non-smoker'. It gets much easier to maintain that mindset the longer you go.
It's not 'magic', and it's not even complex psychology or some sort of mind-trick, it's just about fundamentally reassessing your relationship with your problem substance, and how you go about framing your abstinence in your own mind.