If you're a cheery person, you may have your DNA to thank. Researchers from the London School of Economics and Political Science found that people tend to be more satisfied with their lives if they possess a version of the 5-HTT gene that is more efficient at transporting the mood-boosting neurotransmitter serotonin.
Making joy a goal may not be the best idea. According to a study in the journal Emotion, women who place a high premium on happiness tend to be more depressed, perhaps because they feel disappointed with their failure to meet their high standards.
A rigorous review in the Journal of Alternative and Complementary Medicine showed that for depressed people, finding contentment may be as simple as doing nice things: "Positive activity interventions"—such as performing acts of kindness, counting one's blessings, and writing letters of gratitude—reversed apathy, stimulated the brain's pleasure circuits, and restored happiness.
From the November 2011 issue of O, The Oprah Magazine.