Most people don't think of marathon running as a sport "only" for men or women, but things were very different in 1967.

That was the year Kathrine Switzer, inspired by a coach who told her the marathon was too far for a "fragile woman" like her, became the first woman to officially run in the Boston Marathon.

Back then only men could sign up for the race, so Kathrine had to sign up using her initials, as "K.V. Switzer." One race official actually tried to pull her off the course during the marathon.

Jock Semple, who was famous for pulling "unserious" racers off the course, ran up behind Switzer and tried to rip her bib off. He only stopped when Switzer's boyfriend knocked him to the ground.

Despite the interruption, Switzer finished the race in an an impressive 4 hours 20 minutes. Five years later, in 1972, the race finally allowed women to sign up. But Switzer's journey didn't end there.

Over the years Switzer kept racing - her career highlights include finishing 2nd in the Boston Marathon and 1st in the New York City Marathon - while also hosting TV shows, writing bestselling books, and winning awards for doing both.

This year, the Boston Marathon honored Switzer by retiring her iconic bib number, 261, after she ran one more race wearing it.

The most incredible part of this story? After 50 years, Switzer has only added 24 minutes to her time, finishing this year's race in 4 hours, 44 minutes.

Switzer's determination to do what others told her she couldn't has inspired countless women throughout the decades, and they tell her in person at every marathon she goes to.

"When I go to the Boston Marathon now, I have wet shoulders"”women fall into my arms crying," she wrote.

"They're weeping for joy because running has changed their lives. They feel they can do anything."

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