"I was training to do Detroit," Fitzmaurice told CBC Radio's As It Happens. "It was a beautiful morning and it was perfect running conditions and I felt good. Twenty miles (32 kilometres) is the farthest I've ever done."
Fitzmaurice, 34, said she had figured her time for a half-marathon (21 kilometres or 13 miles) would be about 1:29. When she was still running at 1:31, and not seeing a finish line for the half, she just kept going.
- LISTEN: Meredith Fitzmaurice describes how she won the marathon
"I saw two men farther up ahead of me so ... I followed them," said Fitzmaurice. "I had no one to talk to."
She said that by the time she reached the final stretch, people were yelling at her: "You're in first!" That's when she realized she was about to win the race.
Her time was 3:11:48 — enough to qualify for the Boston Marathon.
"It was a very happy day for me."