Professor of Psychology, University of California, Davis; One of the World's Leading Experts on Gratitude; Editor-in-Chief, The Journal of Positive Psychology; Author, The Little Book of Gratitude (2016), Gratitude Works!: A 21-Day Program for Creating Emotional Prosperity (2013), Thanks!: How the New Science of Gratitude Can Make Your Happier (2007); Co-Author, The Psychology of Gratitude (2004)