BOSTON (CBS) – Four-time Boston Marathon elite runner and Marblehead native Shalane Flanagan has retired from professional running after a 15-year career.

Flanagan, 38, who won the 2017 New York City Marathon and holds the Boston course record for the fastest finish by an American woman, made it official on Instagram Monday. She’s now going into coaching.

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“All I’ve ever known, in my approach to anything, is going ALL IN. So I’m carrying this to coaching. I want to be consumed with serving others the way I have been consumed with being the best athlete I can be. I am privileged to announce I am now a professional coach of the Nike Bowerman Track Club,” she wrote.

Flanagan, a 2000 graduate of Marblehead High School, has also been a Boston Marathon analyst twice for WBZ-TV, in 2019 and in 2017.

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Shalane Flanagan won the 2017 New York City Marathon. (TIMOTHY A. CLARY/AFP/Getty Images)

She was a four-time Olympian and finished in the top 10 all four times she ran the Boston Marathon, including her last race in 2018. Her best performance came in 2014 when she recorded the fastest time ever for an American woman in the race at 2:22:02.

“I hope I made myself a better person by running. I hope I made those around me better. I hope I made my competition better. I hope I left the sport better because I was a part of it,” Flanagan said in Monday’s post, ending it by saying she has one regret.

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“I regret I can’t do it all over again.”