Zach Zimmerman freely admits what he does is a little crazy.
In May, he ran two marathons in 15 days. This summer, he ran four half marathons in four days.
"I felt good enough to run another one on the fifth day too," he said. "But I had to spend the day sitting on a plane (taking a work trip) instead."
Zimmerman is a member of two clubs whose members tick off marathons and half marathons as casually as the rest of us check off items on a grocery list. The minimum requirement to join: Finish two marathons or half marathons in 16 days.
The Marathon Maniacs and Half Fanatics started as local running clubs that now include a combined international membership of more than 12,000 people.
"It's a 'pinch me' kind of thing," said Tony Phillippi, one of the three marathoners who founded the club. "To see that many people excited about and celebrating running is pretty special. Sometimes it gives me goose bumps."
The stories that resonate most with Phillippi are ones such as Zimmerman's.
A 33-year-old state mortgage auditor, Zimmerman wasn't much of a runner until he met his wife, Anne. She persuaded him to start taking short runs with her and then sign up for a half marathon.
Zimmerman was a cyclist who logged many miles, but he also lugged around a significant amount of extra weight. He credits Anne for getting him started and his young daughters for motivating him to get serious about the sport, because running workouts take much less time than long cycling workouts.
He qualified for Half Fanatics in 2010, and in 2012 he decided he was going to run faster, farther and more often. Zimmerman set a goal of running 12 half marathons in 2012. "My wife thought I was crazy," he said. He ran 15.
He also started regularly running the 13.1-mile races in less than two hours, a time many runners set as a goal. And with a proper diet in place, he dropped from 230 pounds to 175. In May, he also qualified for the Marathon Maniacs.
"I feel much healthier now," Zimmerman said.
Marathon Maniacs has more than 7,400 members, and Half Fanatics has more than 4,600. The membership ranges from elite runners capable of winning races to walkers.
"Really, it's about the camaraderie and having fun running," Phillippi said.
Marathon Maniacs started 10 years ago after Phillippi and two friends ran a marathon in Coeur d'Alene, Idaho. Phillippi, Steven Yee and Chris Warren were comparing their racing accomplishments and goals.
All three ran marathons with the ease most runners finish 5-kilometer races with, and all were well on their way to recording more than 100 marathons.
They hatched the idea for a club for lovers of marathons. You didn't have to be fast to qualify. You didn't even have to run. But you did have to complete multiple marathons.
"There are different levels of maniacal," Phillippi said. So the club identified nine of those as membership levels.
The easiest requires running two marathons in 16 days or three in 90 days. The most challenging gives runners 365 days to finish 52 marathons; or 30 marathons in 30 different states, countries or Canadian provinces; or marathons in 20 different countries. All must be official races. Long training runs don't count.