I hate to add to your misery but like the rest say, forever.
You really did a double whammy there. I quit drinking first for a few years and then quit smoking Jan 7th of this year (over 10 years sober now) More power to you.
I find the cravings have to do with emotions more than actions. I used nicotine to stuff my emotions. Now when I'm upset, it's a smoke I crave.
I just use the same methodology I used for quitting drinking: "Not right now!"
Best of luck to you!