CHICAGO (CBS) — The Chicago Marathon is Sunday, and many first-time marathoners are among the thousands of runners participating to raise money for charities.

As WBBM Newsradio’s Bernie Tafoya reports, marathon coach Brendan Cournane says 75 percent of the 400 runners he has been coaching since May are running a marathon for the first time Sunday.

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LISTEN: WBBM Newsradio’s Bernie Tafoya reports

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Their most frequent question, Cournane said, is, “can I do it?”

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Cournane’s mantra is, “Good form will carry you through.” It is what he expects to tell many of the new marathoners again on Sunday, when some will inevitably text him during the race.

“In the last couple of years, I have had messages with runners on the course, with injury questions, or just what they call freak-out questions – ‘I’m freaking out because I’m at mile 20 and I don’t know what to do right now,’” Cournane said.

Last year, after running the Kilimanjaro Marathon in Tanzania, Cournane climbed to the peak of Mt. Kilimanjaro.

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The Bank of America Chicago Marathon begins at Monroe and Columbus drives at 7:30 a.m. Sunday.