Derek Mitchell weighs more than 500 pounds but he's decided to run a 5K race once a month.
He ran one last Sunday in Knoxville, Tennessee.
Why does he do it?
"Just to show it doesn't matter how big or slow, big or small or fast or slow that you are, that a finish is a finish," Michell says. "And that no matter how slow you go you are still lapping everybody who is still on the couch."
Mitchell says he doesn't just run to get in shape but he's also hoping to inspire others to get fit as well.
Along with the 5K races, Mitchell also completed two 10K races this summer. He hopes to run his first marathon in Honolulu in 2016.