In 10 years I've quit smoking twice - one time for one year, another time for 6 months. I just left one cigarette and told to myself if I will smoke that one, I will never ever quit. That cigarette was always with me. Later on, I called it "cigarette of conscience", cause all you need is to prove to yourself (not promise..) you can do it. And if you fail - you feel guilty. It's psychology...
First, three days were so hard for me but reminding to myself "if I will smoke that one, I will never ever quit" helped a lot.
Before deciding to quit I wrote pros and cons. Pros were like smoking is helping to reduce stress what's is bullshit. And a lot of cons like a bad smell in the mouth, fingers, clothing / money to the air / blood circulation <> potency / bad sleep / etc.
The bad thing is I started to smoke again. It happened at the party when I drink too much alcohol. And it continues for 5 years now.
By reading this topic I found the motivation for myself to try to quit again with the same method. From the 1st of September. It's because the week after is my 35th birthday. And I need to prepare myself to stop wasting my money (£300 a month) and my health. Hope - forever.