From Vincent Van Gogh on through Kanye West, the figure of the broody, tortured artist looms large in the popular imagination. But research suggests that the key to creativity has little to do with angst. In researching my book The Happiness Track, I found that the biggest breakthrough ideas often come from relaxation. History shows that many famous inventors have come up with novel ideas while letting their minds wander. In 1881, for example, famed