More than 50,000 runners will make their way through a 26.2-mile race across all five boroughs Sunday.

Some are running for the very first time, while others are veterans of the course.

What You Need To Know

Karen Bdera’s love for running dates back to 1984 when she spotted a sign on an MTA bus that said “Who says women can’t run the world”

Her first race was the 1984 women’s 10K through Central Park. This marathon will be her 715th race

She made many friends along the way, but one in particular stands out for introducing her to her now-husband of 36 years

“The sense of accomplishment when you get to that finish line is just very empowering,” Karen Bdera said.

Bdera would know. She’s completed 24 New York City marathons and has the medals to show for it.

“The whole borough of Brooklyn brings magic to the world,” Bdera said. “I mean, there’s cheering everywhere, there’s 2 million people out there cheering for all the runners.”

As she gears up for marathon number 25, she can’t help but think back to how it all started in 1984, with a sign.

“I was on a bus going to work,” Bdera said. “I was just out of college, and there was this sign on the bus that said, ‘Who says women can’t run the world?’”

That sign, it turns out, was an ad for a race.

“It was something that caught my attention, and as a non-runner, I don’t quite know why it caught my attention, but it did,” Bdera said.

It was for a women’s 10K through Central Park.

“Back in the early 80s, that was a big deal, because there was a whole huge contingency of women’s lib, etc. etc.,” Bdera explained. “And I’m like, ‘I have never run in my life.’”

The runners of that race got a t-shirt, and Bdera got hooked.

Two years later, she finished her first marathon. Now, she’s 715 races in.

Along the way, she’s made lifelong friends. One in particular inspired her to cross finish lines.

“Because she was racing in her 60s, and I’m like, ‘Well, if she can do it, I can do it,’” Bdera said.

Bdera’s friend also helped her find love, saying, ‘Hey, you should meet my son!’

“She kindly introduced me to my husband of now 36 years,” Bdera said.

“Well, of course, when she proposed, I didn’t want her to think I was cheap or easy, so I said, ‘I’ll get back to you,’” joked her husband, Nick Bdera.

For the past three and a half decades, racing has been “their thing.”

“We’re the walking Bderas,” Karen said. “I don’t know how else to put it.”

A love built, in part, on a shared love of a sport.

“We don’t always race together, because now he’s slower than I am,” Karen said. “So I wait for him — he did an awful lot of waiting for me in the beginning.”

“What’s your response to that?” NY1 asked.

“Yeah, it’s sad,” Nick said. “You get old, you get slow. It’s terrible, but that’s life.”

A life filled with thousands of miles — and counting — all thanks to a little sign, spotted on a New York City bus 40 years ago.

“Once you realize you can do it, there’s no reason not to do it,” Karen said.