When Belynda Pinkston started the OUC Orlando Half Marathon, she left behind three women whom she knew well.

One struggled to climb a flight of stairs. Another was embarrassed to ask for a seat-belt extension on airplanes. The third barely beat the patrol cars reopening the streets as she crossed the finish line of her first five-kilometer race, placing last.

Pinkston knew those women, because she was them. That is, until she lost more than 100 pounds.

“I had some staff members, when I was a high-school principal, who were avid (long-distance) runners,” said Pinkston, now an administrator with the Osceola County School District in Florida. “I just said, kind of jokingly, ‘I would like to do that.’

“That someday has come for me.”

And for so many others, like Pinkston, who ran or walked 13.1 miles for the first time. About 3,500 half marathoners were expected to crowd the streets of downtown Orlando, and more than 13 percent (about 470) never have done a race of this length, according to the race’s organizer, Track Shack.

George Poppenwimer and John Gill were first-time half marathoners, too.

“An awful lot of people are 67 and don’t get off the couch,” said Poppenwimer, a retired sales and marketing manager. “I enjoy that I am 67, and I can beat people who are quite a bit younger than I am. That’s a part of it, too. I can still do this stuff.”

Said Gill, who is 51 and runs a company specializing in providing services for the disabled: “This accomplishment means a couple of things. No. 1, I am a motivated person, so I can set a goal and achieve it. No. 2, I am mentally tough enough and in good enough shape to do it.”

Pinkston is in good enough shape now, too. When she started losing weight in 2013, entering a half marathon would have been as unreachable as a star in the sky.

Pinkston’s weight was jeopardizing the life she wanted with her husband, Kenneth, a law enforcement officer.

“As we are nearing retirement, that was an impetus for the life change,” said Pinkston, 53. “Ken says, ‘I want you around for a number of years, and if you keep on the track that you are on now, we aren’t going to be able to take those long walks on the beach together.’ “

Pinkston and her husband began working out together, and she dropped most of the weight over a two-year period, starting in 2013. Once her fitness level improved, the Pinkstons began entering 5Ks.

The longest race that Pinkston has attempted before this weekend is a 10K (6.2 miles). She has increased her training mileage as the OUC Orlando Half Marathon approached. Pinkston got to 10 miles - walking for three minutes, followed by jogging for two - then tested herself by going 12 miles.

She made it.

“When I first started, I had these little messages of doubt: ‘You can’t do that. Your age is a factor. Your weight is still a factor,’ ” said Pinkston, who wants to lose 30 more pounds. “I finally broke that barrier, and I said, ‘I can do this.’ “

“She fought through all of (the self-doubt) and turned into a true champion when it comes to working out,” said Kenneth Pinkston, who has dropped 50 pounds.

Half-marathon finishers in the United States surpassed 2 million for the first time in 2014, according to Running USA. More than a hundred pounds lighter, Belynda Pinkston is excited to join that crowd, something she never thought was possible at one time.

“I got rid of all my clothes as I transitioned from different weight sizes,” Pinkston said. “Part of the reason I held onto the weight was that I had really nice clothes. I found solace in the fact that I donated a lot to Goodwill, and perhaps someone else will put on those clothes and feel the way that I felt.

“That was no longer who I was.”