For you younger people that haven't been smoking long...take my advice and please stop now.
I quit about 2 months ago cold turkey with no relapses. It was actually incredibly easy for me to quit. I just decided to quit and not buy another pack.
My biggest test was the first time I got really fricked up after quitting. Passed even with tons of people smoking around me and it's been smooth sailing.
I'm pretty happy I decided to quit. I definitely feel better, especially after a night of heavy drinking since I wasn't chain smoking. Goddamn, some mornings my lungs would feel fricking terrible.
I smoked a little under 4 years and just turned 24, fwiw.