With little training he pushed the pace and as soon as he crossed the finish line the race took a terrible turn.
"My body was totally stressed and my fluids were building up in my lungs, because I couldn't clear that and it was a lot more serious than I took it," says Roosa.
Roosa collapsed and was having trouble breathing. It just so happens he fell at the feet of television host and professor of surgery at Columbia University, Dr. Mehmet Oz.
Dressed in a super hero cape to go along with the theme of the 5K Dr. Oz dropped to his knees to attend to Roosa. Roosa says at first he didn't receive the gesture to kindly.
"Held me on the ground, made sure I didn't get up, which really torqued me off, I wasn't very nice to him."
Dr. Oz wasn't deterred by the grumpy reception. He continued to assist Roosa and the attitude soon changed to appreciation.
"Knowing you have this expert dude out there taking care of you like that and knowing this was genuine, this wasn't something he put on because he had to. It was like, no I want to be involved, this is a serious scenario and I can help."
The doctor's care didn't stop there. Roosa was transported to the hospital where he was quickly stabilized. About a half hour into the stay, Dr. Oz made a bedside visit.
He even consulted with Roosa's emergency room doctor to ensure a clean bill of health.
"Dr. Oz was more than caring. He was concerned, he was kind, really helped us out a ton," says Roosa.
After a 30 hour stay at the hospital and a brief brush with fame, Roosa walked away with a new outlook on exercise.
"Listen to your body. We all need to understand the parameters we can live within and how far you can push yourself, because dire things can happen."
And a new friend for life.
“He's already said, hey any time you are in New York City stop by the studio, we'd love to hang out."
There was early concern of a cardiac event, but Roosa's final diagnosis was dehydration and body stress.