All eligible participants must attend an orientation session when the investigators will explain the study in detail. After this session, interested participants will complete a consent form and the investigators will collect blood pressure, resting heart rate, body mass index (height/weight), and a carbon monoxide sample to confirm eligibility. The investigators will then explain the physician consent process (all eligible and interested participants must obtain consent from a physician or clinic that they have seen in the past year to confirm that it is safe for them to participate).