The famous Washington D.C. race is now flatter and faster.
Lance Corporal Kerr's act of kindness has made him an overnight hero.
Over 30% of runners will be debuting.
The event honors the establishment of the United States Marine Corps.
Runners now have the option to transfer their bib to someone else.
He did it under two hours.
Nearly 8,000 runners will participate in the event.
He is doing it to celebrate his dramatic weight loss.