Over the last 12 years, 101-year-old Fauja Singh has completed nine marathons.
Singh, often called the "Turbaned Tornado," was a farmer in Punjab, India, before moving to England and taking up running at age 89.
His best public marathon time is reportedly five hours, 40 minutes and four seconds.
Singh is believed to be the oldest marathon runner in the world, but he can't be verified by Guinness World Records because he doesn't have a birth certificate.
This Sunday in Hong Kong, Singh will complete his final 10K before retirement.
"I am hurt by the fact that I am going to retire," he told the AFP, via an interpreter.
"I do not really want to hear the word 'retire' because I can still run and jump on a bus … I fear that when I stop running, people will no longer love me. At the moment, everyone loves me."
Jessica Testa is a national reporter for BuzzFeed News and is based in New York.
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