Oprah talks to Harvard Professor, social scientist and author Arthur Brooks about his #1 New York Times bestselling new book, From Strength to Strength: Finding Happiness and Success at Every Stage of Life. Arthur explains that by refocusing our priorities and habits, we can set ourselves up for joy and deepening purpose in the second half of life. He introduces the concepts of a fluid intelligence curve and a crystallized intelligence curve and how we must move from one to the other at some point in our lives to increase our happiness.