Sleep, lots of it. Can't smoke when you sleep lol. Sounds stupid but it's helped me with quite a few things like that, sleeping 15 hrs a day...Main thing is, like was mentioned above, YOU have to want it. You might say you need to quit but your brain's still saying it's ok. So, until you get it engrained in your head that you really can't afford to fail this test, you won't feel the need to quit.

And I prefer the term "habit forming" to addictive in this sense. Like was mentioned, it's not per-say chemically addictive (that we can find yet), but some people have a high predisposition to addiction and anything can become habit forming in these individuals...Bad habits are often termed addictions even when they are not, it's all about whether or not it interferes with your daily life in negative ways. Marijuana should never be abused to the point of smoking pounds of it, the good is all lost by that point and you're quite likely putting yourself at serious risk down the road.