The New York City Marathon is this Sunday, and thousands of runners will be racing through all five boroughs. On today's Please Explain, we'll find out what’s involved with completing the marathon’s 26.2 miles. David Willey, Editor-in-Chief of Runner's World magazine and Charlie Butler, executive editor of Runner's World and co-author of The Long Run: A New York City Firefighter's Triumphant Comeback from Crash Victim to Elite Athlete, join us now to talk about how runners race, train, deal with injuries, and how regular people can start running for exercise.