The former Bachelorette star completed the race on Monday for his friend Zohn, who was unable to take part as he is being treated for a recurrence of Hodgkin's lymphoma.
Sutter told the Boston Herald that his "inspiration" during the race was Zohn.
"But no matter what I did physically, it's nothing compared to what he and other people with cancer do every day," he continued. "That kept me going."
Sutter also revealed that he would consider taking part in the Marathon again, saying: "If you asked me at the finish line I would have said, 'No way', because it's so painful and you have to train for so long. But this is a special town and the race has so much authenticity, I can't rule it out."
Zohn had a stem cell transplant in February and has said: "It's not easy, but I'm getting stronger every day."