Matthew McKay, Ph.D., is a professor at the Wright Institute in Berkeley, CA. He has authored and coauthored numerous books, including The Relaxation and Stress Reduction Workbook, Self-Esteem, Thoughts and Feelings, When Anger Hurts, and ACT on Life Not on Anger. His books combined have sold more than 2.5 million copies. McKay received his Ph.D. in clinical psychology from the California School of Professional Psychology. In private practice, he specializes in the cognitive behavioral treatment of anxiety and depression.