Lasting happiness may be more likely to come from a habit of heartfelt gratitude than from a job promotion or winning the lottery, according to University of California research psychologist Sonja Lyubomirsky and her colleagues, who’ve spent 18 years looking into the nature of this sometimes-elusive feeling. Their most surprising discovery is that true happiness depends far more on how we live our lives than what happens to us: About 50 percent of a person’s happiness comes from his or her “biological set point,” while only 10 percent of happiness seems to depend on circumstances, like finding a great spouse or losing 10 pounds. That leaves 40 percent of happiness dependent on intentional activities, which this book is designed to teach. Lyubomirsky’s research-based “happiness program” includes a dozen activities that studies have shown to qualitatively improve the happiness bottom line: everything from practicing gratitude and ending overthinking to cultivating optimism and practicing acts of kindness. The book also includes happiness assessment tests, guidance for finding the exercises that will best suit you and a useful supplement on depression. A satisfying read that will help even the most skeptically inclined feel better than they knew they could.