A few years ago, 2011 Glamour Woman of the Year honoree Arianna Huffington was on the set of Morning Joe, when she noticed co-host Mika Brzezinski wasn't herself. Brzezinski explained that she hadn't been sleeping. Between her high-power job, her family, and all the little things that come up every day, "I wasn't there. I was a shell of a person," she said. That story -- along with Huffington's own scary brush with working to the point of total exhaustion -- helped inspire Huffington's new book Thrive: The Third Metric to Redefining Success and Creating a Life of Well-Being, Wisdom, and Wonder, and captivated the audience last Thursday night, at the opening of the Thrive conference in New York City.