She’s still not really sure how it happened, all those months ago.

She heard a radio ad, and “it sounded fun.” Never mind that she wasn’t a runner — when she started training, she couldn’t make it a full mile.

Irene Alltucker realizes now just how crazy the idea really was. But for some reason, she was convinced she could do it. Last October, she crossed the finish line in San Francisco. It took her 4 hours, 44 minutes, and she walked a portion of the race.

But she was a marathoner. And she realized:

“Really, if I can do it, anybody can,” Alltucker says.

More and more often, Everyman is.

Early Sunday morning, Alltucker, 47, will be among several thousand people gathered at the starting line near Hayward Field. A few elite runners will bound away like gazelles. The vast majority will shuffle along at various paces.