Are you a busy runner who wants to run a marathon, but doesn't have time to read the usual 300-page marathon book written by an intimidatingly intense professional? How does 26.2 pages sound instead? Eric Cohen, a runner who is about as average as they come, boils down the insanity that is marathon running into just four simple principles: (1) Respect the distance. (2) Every body is different. (3) On some days, you're the unstoppable express train, and on some days, you're the bus. (4) And if Daniel Murphy can play second base for the New York Mets, you can run a marathon.