Even though I have had some rough times (not often) with urges the quit has been much easier than my past attemts and I do think it's all about acceptance. When I was in denial about how serious and progressive my copd was, quitting seemed like a choice and it was really tough. I would tell myself when I caved that I could always quit at a later time. Getting as sick as I did and it hit that it really wasn't a choice and I would not live long without making changes I finally accepted that I had to do this and most of the time it really hasn't been difficult.
Keeping expectations low and acceptance high has made me a much happier person as well.