Only one more to go.

Haydar, 62, wants to run 26 Boston Marathons in a row. That will be 681.2 miles, or about 1,092,000 steps, he says.

And why is he running 26 marathon courses in 26 weeks, and urging everyone else to join him for as much of the route as they can?

“It makes you realize that nothing is impossible,” he said.

So far, about 15 people — including his wife, Warde, and visiting daughter, Sue — have joined sporadically in the “26for26” quest. One week, six runners were there, other times three or four. 

But usually it’s just the slender Haydar and his friend Bill McCabe, 59, of Stoneham, who has joined him for every run and says “God willing” and barring an epic catastrophe, he plans to make all 26. 

“I got roped in,” McCabe said. “I thought this was the craziest thing I’d ever heard, and I decided to do it because of the challenge. It’s an endurance test.”

“It’s taken a lot out of my body,” he added, after chugging over the yellow finish line on Boylston Street, on Sept. 23, for the 24th time. “My Achilles tendons are bugging me and my left hamstring has been hurting since mile 17. Normal people get beat up doing this.

“But not him,” McCabe said, pointing to a chipper Haydar, who had crossed the finish line almost an hour earlier, barely sweating, in a relaxed time of 3 hours, 29 minutes. “He’s a cyborg.”

Chris Baker, a Quincy resident who drives a van that takes the runners at 6 a.m. from Quincy’s Marina Bay to Hopkinton , and follows them with water for Haydar and a more elaborate smorgasbord of liquids and energy-boosting snacks for McCabe, has nicknames for both men.

Haydar is “Superman” for obvious reasons, Baker said.

McCabe is “Ironman” for his grit and determination, and because in July he did a half Ironman race on a Saturday — a 1.2-mile swim in Lake Mascoma, a 56-mile bike ride, and 13-mile run — and still the showed up the next day to run from Hopkinton to Boston.

“It’s like ‘Groundhog Day,’ when we see that Hopkinton sign,” said McCabe, referring to the movie that has Bill Murray repeating the same day over and over. “When you get close to Cleveland Circle and start seeing trolleys, it does cross my mind to jump on one, or take a cab.

“But I do this for my [eight] grandchildren — to show that you can do anything if you never give up,” he said. “You don’t have to be the best; you just have to keep going.”

For their part, Haydar and McCabe call 31-year-old Baker their “secret weapon” and say the venture would be logistically near impossible without his volunteer commitment. Baker has driven the van every week, even after he lost his fiancée, who died of complications from a long illness. 

McCabe said he started running about five years ago when his doctor told him he had high blood pressure and high cholesterol and needed to go on medication. Instead McCabe changed his diet and started running. He lost 32 pounds — he’s down to 162 at 5 foot 10 — and lowered both his blood pressure and cholesterol. And he caught the running bug.

Haydar, a property manager in Quincy, first took up running in the 1980s when his daughter was on her school track team and needed a practice partner. He had played soccer as a youngster on the streets of Beirut but never was an athlete.

The first time he ran with Sue he “went about 200 feet and just about collapsed,” Haydar said. “The 200 became 300 and so on [until] finally I was able to do the 1.9-mile loop [around their Marina Bay neighborhood] without stopping. I thought I was a hero when that happened.”

It wasn’t until 12 years ago, though, that Haydar started running seriously, joining the L Street Running Club in South Boston at the urging of a friend. On the first run, a 5-mile circuit around the UMass-Boston campus, Haydar finished dead last, but was thrilled that he’d survived. He quickly discovered the joy of running, and found that he was a natural distance runner.