The how, why, what, when, and who of happiness: Mechanisms underlying the success of positive activity interventions.

M ost people want to be happy (Diener, 2000) and they seek happiness in a variety of ways—through achieving greater income or more prestigious careers, living walking distance to the ocean, or buying a shiny new car. Evidence suggests, however, that changing one’s life circumstances (e.g., marital status, career, location, and income) is not the most fruitful path to greater well-being (Sheldon & Lyubomirsky, 2006a). Instead, simple cognitive and behavioral strategies that people can employ in their daily lives have been found to reliably improve happiness (Sin & Lyubomirsky, 2009), including its hallmark, positive emotions (Diener, Sandvik, & Pavot, 1991; Urry et al., 2004). Th ese strategies do not involve making major shift s to people’s current life situations and can be used by anyone, regardless of their genetic make-up. Although possessing the capacity to increase one’s own happiness may sound too good to be true, the development and understanding of happiness-boosting strategies have come a long way since Fordyce (1977, 1983) published his fi rst successful attempts at intentionally increasing happiness levels in his classrooms. Since that time, research has accumulated to convincingly suggest that a large portion of happiness may be under people’s control through the activities they choose and how they construe and respond to situations in their lives (Lyubomirsky, Sheldon, & Schkade, 2005). A common argument from skeptics is that people’s happiness levels are genetically determined and cannot be substantively changed. Despite persuasive evidence from twin studies that well-being levels are strongly infl uenced by genetics (Lykken & Tellegen, 1996), more recent research suggests that genetic infl uences on happiness might be weaker than originally thought, with environmental infl uences explaining a large portion of individual diff erences in happiness (Røysamb, Harris, Magnus, Vittersø, & Tambs, 2002; Stubbe, Posthuma, Boomsma, & de Geus, 2005). Furthermore, research on gene-environment interactions suggests that biology and