If you are eligible to take part in the study, you will be randomly assigned (as in the toss of a coin) to one of three treatment groups. Participants in the first group will receive Bupropion. Participants in the second group will receive Varenicline. Participants in the third group will receive a placebo. A placebo is a substance that looks like the study drug but which has no active ingredients. You will have an equal chance of being assigned to the Bupropion, Varenicline, or placebo treatment group. Neither you nor your counselor will know to which group you were assigned.