Each chapter David tells a bit about what happened in his life and by the end of the chapter, he throws a challenge for us. I think those challenges are a great way of understand life and his stories also help to give meaning to those challenges. His stories are great, vivid and very inspirational.
One of the few books I read that I really thought everything was so meaningful and worth doing.
By the way, if you think that your life sucked at some point or still sucks and you feel like there is no way you are going to fix it, you gotta read his story and try those challenges. I have read many books about psychology and personal development that I can say his approach to improve in life is universal and very effective.