How did you quit? I really want to quit right now, I even switched for e-cigarettes but I came back to normal after one week.
Hope that helps, it worked for me.
Actually the only time I managed to quit smoking for more than a few weeks when I was away from my friends/girlfriend for a five months and had no one smoking around me all day. It's easy for me to quit, it takes me a -pretty painless- couple of days. But after a while I relapse.