The most popular course at Harvard University this semester teaches happiness. Positive Psychology, a class whose content resembles that of many a self-help book but is grounded in serious psychological research, has enrolled 855 students, beating out all other classes. 35-year-old Tal D. Ben-Shahar, the lecturer who teaches the course, describes how students might increase the likelihood of transformative, positive experiences through exercises that vary from cultivating a sense of gratitude for the beautiful things in their lives and meditation, to taking the time to really listen to music. This article includes more on Ben-Shahar's teaching approach and his six tips for happiness.