You need to appreciate that although the really hard cravings to get past all pretty much happen in the first month or so, you will still be challenged at times and some times there is no clear reason why but, the challenges you will have to face will become fewer and less intense as time goes by. That's just how it works for all of us. Slowly .... very slowly you will become more and more comfortable as a non smoker. It's pretty common knowledge that you need to pretty much put in a whole year as a non smoker to have faced all the challenges you are likely to face. Even after that, you will still think of smoking you just won't want any part of it because you will realize that it never did even one good thing for you (or at least you should realize that after 1 whole year). So, carry on and trust in both the quitting process and yourself. If you have made it to the 3 month mark, there's no reason you can't be a non smoker for the rest of your life