Gretchen Rubin

Gretchen Rubin is a happiness researcher and bestselling author of "The Happiness Project," "Better Than Before" and "The Four Tendencies." Her most recent book is "Life in Five Senses: How Exploring the Senses Got Me Out of My Head and Into the World." She's also host of the popular podcast, Happier with Gretchen Rubin, and founder of the award-winning Happier app, which helps people track their happiness-boosting habits. Follow Gretchen on Twitter and Instagram.