I quit smoking similarly -- a bit of a hangover, an illness, followed by a terrible week of digestive issues (likely due to the quitting smoking) and after the week, not starting again wasn't a problem.

Now I wish I'd never done it in the first place, but here we are.

I think it just comes down to feeling unable to procure the item of your addiction -- and the mental position to want to leave it behind. I couldn't properly quit until that point... pure resolve. Pure resolve, and being stuck in bed in terrible pain for a week (haha?)