Getty Images/John MooreIn the 1990s, a psychologist named Martin Seligman led the positive psychology movement, which placed the study of human happiness squarely at the center of psychology research and theory. It continued a trend that began in the 1960s with humanistic and existential psychology, which emphasized the importance of reaching one’s innate potential and creating meaning in one’s life, respectively. Since then, thousands of studies and hundreds of books have been published with the goal of increasing well-being and helping people lead more satisfying lives. So why aren’t we happier?