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A retired Memphis dentist ran at least one mile, every day for 40 years.

Rain, sleet, snow or injury never stopped Jon Simpson, a septuagenarian, from lacing up and enjoying an early morning, half-hour run near his home, The Wall Street Journal reported.

"I'm just glad to get my first 40 (years) under my belt," he joked to the paper.

There are five people, all men, in the U.S. who've accomplished the benchmark. Their backgrounds are diverse; one's a writer from California, another a track coach. These are not world-class athletes seeking multimillion-dollar endorsement deals from, say, Energizer Batteries. No. These are runners who've dealt with broken ankles and busted knees for nothing more than the sake of running. These are competitors in a race with no clear finish line.

Jon Sutherland, 60, the California writer, once ran with a broken hip and keeps a list of his "50 dumbest runs," which he told the paper is under constant revision. Yet he reportedly considers himself one of the more sane runners of the group. "One guy told me he once ran on the deck of a boat in the middle of a hurricane."

Click to read more on this story from WSJ.com