It'll pass. Don't blow of 4 months of abstinence. I can tell you that when I quit, the feeling of failure I would have felt if I drove to the store to buy a pack bothered me much more than any cravings.
This is me. I only smoked for about 3-4 years, but even that short an amount of time smoking is hard to kick. I've now been smoke-free for 2 years as of November. 2010, we had a Thanksgiving Eve show, I had a cold and my voice was fucked. I thought "Well, let me hold off smoking til the show has come ond gone. It's only a couple weeks away and maybe it'll help". Oddly, I felt zero ill effects form stopping. It sometimes made me feel like shit inside anyway. So when the gig came and went, I told myself "No withdrawal symptoms. Why continue?" So I didn't.
Now, whenever we're drinking, especially if it's been a lot, I really do have the urge for one. I continually, even now, have to tell myself that even so much as one drag off of a cigarette will reset EVERY SINGLE DAY of my progress back to zero and I will be a failure and a loser. I don't want to be a failure or a loser. Well, at least not any MORE so than I might be. So with that mindset, I brush off the desire and move on.
FYI, I'm not calling smokers and people who have a hard time quitting failures or losers. I'm simply saying that this is why I have to tell
myself in order to keep my head on straight.
As mentioned, the feeling of victory you'll feel after fighting off the urge and moving on feels far better than what the cigarette will offer you.