Over the past several decades, a new science of subjective well-being has produced insights into the factors that make people happy—from cultivating strong relationships to pursuing the right goals. Drawing on these empirical findings, the investigators created a comprehensive 12-week intervention program, ENHANCE: Enduring Happiness and Continued Self-Enhancement. The investigators multimodal program is designed to teach people essential skills in order to produce sustainable changes in behavior and, as a result, long-lasting increases in happiness. To test the effectiveness of ENHANCE, the investigators designed a six-month randomized clinical trial. Participants will be assigned to an active treatment group or a waiting group control. They will complete baseline assessments, and follow-up assessment at three and six months after the start of the intervention. These assessments will contain measures of subjective well-being and objective measures of health, as well as a variety of psychological mediators (e.g., psychological needs) and moderators (e.g. personality). The investigators will thus be able to explore not only whether ENHANCE works to improve well-being, but also why and how ENHANCE works.