"Doing 26.2 is not my kind, I only make half way," said David Schmitt.
Schmitt is one of the Special Olympics athletes trained by Daniel Tun, a recreation instructor at Chicago Park District's Welles Park.
Schmitt's main focus is training athletes with developmental disabilities.
"Special Olympics training and getting them ready for competitions, that take places year around," said Tun.
He is also running the marathon on behalf of them.
"I think the awareness running for the Special Olympics is the most important piece of running of course, the actually finishing the race is just as important to you, but raising the money and knowing that the funds are going to other athletes within the park district, within the Special Olympics community, is just as important," Tun said.
Bank of America Chicago Marathon Executive Director Carey Pinkowski says. since 2002, they have raised $42 million for their charities.
"We're meshing together individuals that are challenging themselves," said Pinkowski. "They're dedicated, they're committed to the marathon, they're also committing to our associated charities and helping these charities out in a time when they really need the additional funds."
It's not just about raising money, it's also about encouragement.
"Working with these athletes, it's incredible, because they share the same sort of goals that you do as a runner, as an athlete. You know, they face just as many challenges as we do. Seeing them practice and work hard everyday, and to reach those goals, and during competitions, even during practices, it brings a good feeling to you as a coach," said Tun.
Special Olympics athletes like Judy Gumber understand the importance of being part of Bank of America Chicago Marathon's 123 charities.
"That's important so that every other people who are handicapped can come to the Special Olympics, and so the volunteers can come, so that all the volunteers can come to the Special Olympics and help them," Gumber said.
"You're running for a cause that you work for, athletes that you see everyday," said Tun.
Tun is hoping to finish in three and half hours.