What began as a gag gift for Charles Hunter turned into a full-fledged fitness hobby.

Last fall Hunter watched his 4-year-old daughter, Maggie, learn to ride a tricycle. It got him to thinking about the learning process of riding a tricycle and, for whatever reason, to thinking about unicycles and how he had never learned to ride one.

"Later I jokingly asked one of my buddies if he had ever learned to ride a unicycle, and when he responded no, I told him, ‘We better get on that,’" Hunter recalled, laughing at the memory. "I said that if I didn’t learn now, it was never going to happen."

The idea was fleeting.

But on Christmas Eve the same friend bought Hunter a unicycle as a joke — and Hunter took it as a challenge. By the end of the following day, Hunter could ride about 20 feet. The next day he bought his friend a unicycle, and within a week both men had placed orders for three more unicycles.

They were hooked.

"If you had asked me six months ago if I’d ever be stoked on unicycles, I probably would have said no," said Hunter, a 36-year-old attorney who now rides a mountain unicycle — called a "muni" — on hiking trails on the weekends. "Now there’s really no downside to me."

Unicycles are the one-wheeled cousins to the bicycle and have a history that dates back more than 100 years. Unlike bicycles, the typical unicycle has no gears or chain to move it and no brake to stop it. Its pedals are part of the wheel. Push on the pedals and you move the wheel — forward or backward.

And the entire weight of the rider sits over the wheel, making the simple act of balancing on a unicycle the first challenge to overcome.

Although he’s an avid hiker and surfer, Hunter was surprised by the physicality of riding a unicycle. It worked muscles he rarely used, and he was sweating after just 20 minutes of riding around the cul-de-sac where he lives in Hawaii Kai. He’s even lost a few pounds since hopping onto a one-wheeler.

"Like bicycle riding, it’s a great workout for the legs and core," he said. "You’re doing it and having fun, and you don’t even realize you’re working out. It’s a superentertaining way to get into shape."

While unicycling has long been associated with circus acts and acrobats, the modern evolution of this distinctive mode of transport has come to include off-roading, free-styling and touring models. Hunter takes his unicycle on hikes, across deserts and around city centers, often garnering smiles and nods of approval from onlookers.

"It’s such a silly, weird thing to try and ride a wheel around," said Hunter, who regularly rides his "wheel" in the neighborhood. "People are always stoked when you ride by. It makes people smile and that’s awesome. I can’t count the number of high-fives I’ve gotten when riding down the trail at Maka­puu. You can’t take yourself too seriously when you ride a unicycle. It is a completely ridiculous activity."

Hunter started by balancing on the unicycle on the deck of his home, holding onto the railing and just getting a feel for it. Then he inched his way across the deck, still holding onto the rail, until he could pedal it on his own.

"It’s very addicting," he said. "At every stage of the learning process, there’s positive reinforcement. And every time you go a little farther, you want to learn more. There’s really no limit on how far you can go or how much time you can spend on it. It’s really fun."

He’s still working on hopping up stairs and riding backward. (Right now he can backpedal about 50 feet.) And there are other skills he wants to hone, like mounting the cycle without holding onto anything and idling in place.

"You can always get better at doing the basic stuff," he said.

Hunter loves that he can go on rides with his daughter, who’s now riding a bicycle with training wheels. She talks about learning to ride a unicycle. And when the surf is blown out or he has to work late at the office, he can still get in a quick workout by riding around the block.

"Conditions are always good," he said about unicycling. "Even if it’s raining and windy, there is always somewhere to ride. You just need a little shelter and area big enough. You can spend hours perfecting different skills and never go outside of a 400-square-foot box. Rain or shine, day or night, there is always a way to ride."

"Good Fit" spotlights inspiring fitness stories of change, self-discovery and challenge, and other fitness-related topics. Tell us what motivates you and how you stay fit and healthy. Email features@staradvertiser.com.