Becoming happier takes both a will and a proper way: An experimental longitudinal intervention to boost well-being.

An 8-month-long experimental study examined the immediate and longer term effects of regularly practicing two assigned positive activities (expressing optimism and gratitude) on well-being.More important, this intervention allowed us to explore the impact of two metafactors that are likely to influence the success of any positive activity: whether one self-selects into the study knowing that it is about increasing happiness and whether one invests effort into the activity over time.Our results indicate that initial self-selection makes a difference, but only in the two positive activity conditions, not the control, and that continued effort also makes a difference, but, again, only in the treatment conditions.We conclude that happiness interventions are more than just placebos, but that they are most successful when participants know about, endorse, and commit to the intervention.