Book excerpt: Scientists and academics have spent entire careers investigating what makes people happy. But hidden in obscure scholarly journals and reports, their research is all too often inaccessible to ordinary people. Now the bestselling author of the 100 Simple Secrets series distills the scientific findings of over a thousand of the most important studies on happiness into easy-to-digest nuggets of advice. Each of the hundred practices is illustrated with a clear example and illuminated by a straightforward explanation of the science behind it to show you how to transform a ho-hum existence into a full and happy life. Believe in yourself: Across all ages, and all groups, a solid belief in one's own abilities increases life satisfaction by about 40 percent, and makes us happier both in our home lives and in our work lives. Turn off your TV: Watching too much TV can triple our hunger for more possessions, while reducing our personal contentment by about 5 percent for every hour a day we watch.