Good luck. I've stayed quit for almost 10 months after smoking a pack a day for 7 years. Unfortunately, the first 2 days are a cake walk compared to the next week. The thing is that once you've been smoking that long, it becomes a part of your lifestyle. For example, every morning when I walk to work (I work in NYC), I'd always light up a cigarette as soon as I walk passed certain spots like this bank and coffee shop. I did it out of habit because when I lit up a smoke at those spots, by the time I finished, I'd arrive at my destination.
So when I quit, out of habit I immediately wanted to light one up everytime I passed that bank. This is what is called a "trigger" which are situtations that make you want to light one up. Since you have been smoking for so long, I'm sure you have dozens of triggers like I did, for example after eating a meal, watching a TV show at home, playing Counter-Strike etc. The hardest part is to resist the triggers which is why it is a good idea to switch habits (for example, I took a different route to work so I would avoid the certain spots that I always lit up a cig).
Even now, 10 months later I still get a small urge to light one up but that is all mental. I used to spend $200 a month on cigs so I switched that to spending $200 a month on video games (It's freaking amazing how much $200 gets you per month
). I created a massive backlog and it seemed a "waste of money" spending so much, but at least you get something in return rather than spending it on smoking. It should get a lot easier about a month later but the first 2 weeks were horrible (BTW, I know you're thinking how the heck you are going to wait an entire month but you just have to take it one day at a time).
Edit - Here is a pretty good website that I stumbled upon all those months ago.
http://whyquit.com/