Hang in there. Every day that goes by, the desire diminishes a bit. The first couple weeks are the worse.
I quit cold half a dozen years ago. Like you, I had roughly a half pack a day habit when I quit. I'd been smoking around 35 years.
The first week or so it's a real physical battle, fighting the urge for nicotine. After that, it starts to become more mental and a matter of breaking habits.
It ain't easy, but it's a battle you can win. And one worth winning.
