Marlo Thomas and Phil Donahue at Live Talks Los Angeles discussing their book, "What Makes a Marriage Last: 40 Celebrated Couples Share with Us the Secrets to a Happy Life."

What makes a marriage last? Who doesn’t want to know the answer to that question? To unlock this mystery, iconic couple Marlo Thomas and Phil Donahue crisscrossed the country and conducted intimate conversations with forty celebrated couples whose long marriages they’ve admired—from awardwinning actors, athletes, and newsmakers to writers, comedians, musicians, and a former U.S. president and First Lady. Through these conversations, Marlo and Phil also revealed the rich journey of their own marriage.