This is a book about ultra-athletes, people who have pushed themselves to super feats such as; swimming the English Channel, running in six day running events, bicycling across America, etc.. The author herself swam the English Channel. she also swam five laps around Manhattan Island. I cannot picture myself accomplishing these feats, nor do I attempt to try them. This book was not written to convince anyone to push themselves to match or exceed these high levels of athletic prowess, but merely to point out that we all posess the potential to do so much more than we are now doing, and even more than we can visualize ourselves doing. These authors really should collaborate more often, as I feel this was an excellent book, and I would like to read more of their writing. I actually went out and exercised after reading it!