I'm not sure - it's so different for everyone.
This time I think the main difference is that I really have had enough. Even before I started this latest quit, I had to force myself a little to have a cigarette. I'd be watching TV just a few minutes before going to bed, take out a cigarette, and hold it in my hand sometimes 10-15 minutes before I got around to smoking it. Then I'd think, "Should I bother? Yeah, might as well. It's so good."
I think the trick was that I've tried to quit so frequently over the past year or so. Every time I went back to smoking, I only gave myself a few months at best before trying again. I think I wore my motivation to smoke out.
And I keep telling myself: I've had enough. I'm an ex-smoker. Keep calm and carry on. Over and over.
There's also the patch. That's really working for me. This latest quit I haven't selected and craving level higher than 2 yet - and after just one week I'm selecting a craving level of 1.
I'm sure I'll have some discomfort to deal with transitioning to the lower dose patch in 5 weeks - but, that's fine. That'll be longing for the patch, not a cigarette.
One more good thing I noticed today: I sleep better. I wake up more refreshed. AND my eyes are more clear and white.