He doesn't think it's possible, at least at the moment.
The life-to-date value raised is estimated at $1.1 billion.
He will move up to the 26.2-mile distance next spring in London.
Check out some of the career highlights from one of America's top marathoners!
The Ethiopian is the pre-race favorite.
He has been a force in the race since its founding five years ago.
He would also like to set a British record.
The Welsh world-record holder ran a blazing 2:08 that year.
The double-Olympic gold medalist learned a lot about his race.
Priscah Jeptoo and Tsegaye Kebede are the newly crowned champions.