RecruitingBehavioural interventionPartnering to Enhance Emerging Adults' Response to ProgramsThe goal of this clinical trial (CT) is to learn more about emerging adults' and their peers. Here, we will see how co-participating with a peer in health program might impact brain and behavior change over time. Eligible youth will be invited to come in for a "Participation Day," during which they and a peer will independently complete questionnaires. With a peer, they will then complete a short health program, and undergo a brain scan (fMRI) while completing activities. Our study team will reach out to each participant individually again 3, 6, and 12 months later to learn about health behaviors over time.