Yes I have quit after 25 years of smoking a pack a day and yes it was difficult in that I quit cold turkey at least 25 times. I believe it's all in your head, and that nicotine leaves your system completely in 3 days, so after 3 days, for me personally, I believe it was all psycological when the cravings came. You may have to quit several times before it really sticks.
For me it was that I got tired and embarassed of the cigarette smell on me and in my house. I had an ozone machine run for 2 days to remove the smell. Since that was so much trouble it motivated me to quit completely and not even think about it, but it took 25 relapses to get to this point. So don't beat yourself up if you fail -- just keep trying.
Also it's really nice not to have to worry if I have enough cigarettes, and I am saving money as well.