The purpose of this study is to better understand tobacco outcomes using a commonly prescribed stop smoking medication (varenicline) and financial incentives for adults who also use cannabis. Varenicline is not FDA approved for e-cigarette cessation, but is FDA approved for cigarette cessation. We are also interested in how cannabis/marijuana and tobacco interact during a tobacco quit attempt. All participants will receive e-cigarette cessation treatment for 12 weeks. To qualify, participants must be between the ages of 18-40 and use both tobacco and cannabis. Participants do not need to be interested in quitting cannabis to qualify. This study is being conducted at two sites: the Medical University of South Carolina in Charleston, SC and Behavioral Health Services in Pickens, SC.