Why Gratitude Leads to Happiness

The Declaration of Independence says we're all entitled to "life, liberty and the pursuit of happiness." How is happiness measured… and how can it best be pursued? We speak with a woman who says she knows at least one way: gratitude.

Sonja Lyubomirsky is Professor of Psychology at the University of California, Riverside and author of

The How of Happiness: A Scientific Approach to Getting the Life You Want

.