A workout routine can become about as appealing as a diet without chocolate. Which makes it hard to stick with. "Being an athlete, I’ve gone through that whole serious training program, the same regimen every day, the grind," said Jennifer Lee, 32, a professional stand-up paddleboarder, before a morning workout at Kaimana Beach with her boyfriend, Alfred Van Gieson, a 34-year-old canoe paddler.

"How do you make fitness fun?" Lee remembers asking herself.

Intrigued by obstacle races, a growing trend, the couple tried the Makahiki Challenge mud run at Kualoa Ranch last year. They found just what they wanted: a fun fitness activity they could do outdoors with friends.

"We had a total blast," Lee said.

"And we made new friends," Van Gieson added.

Although crawling through deep, sludgy mud beneath wires might not be everyone’s idea of fun, Van Gieson said he enjoyed getting dirty, especially sliding down a steep, muddy hill on his butt.

"The hardest obstacle was walking through an ice bath in a dumpster," he said. "It was torture."

"I hated the cold!" Lee said with a laugh.

What she loved was the feeling of achievement. "I looked back at the valley and thought, I ran up that mountain, went across those monkey bars, climbed over that wall," Lee said.

Although they had watched videos beforehand, she noted, "Obstacle races change the course every year so there’s a bit of a surprise. That’s what makes it fun!"

She’d never climbed any rope, much less knotted strands for scaling walls 10 to 20 feet high, but found she could do it thanks to the non-routine fitness sessions she and Van Gieson designed. Their workouts incorporate hiking, surfing, playing with their children, running, paddling and core strengthening, as well as exercises they learned from doing CrossFit and core power yoga.

"We try to use our surroundings, get out in nature," said Lee, who has paddled in oceans around the world and down a river in Utah.

Van Gieson, a superintendent for Matson and an Air Force reservist, paddles for the Leeward Kai Canoe Club, founded by his grandparents, and on his own; he won thesingle-man outrigger 2012 world sprints championship in Calgary, Canada.

As a change from his competitive training, he appreciated the low-key vibe and community spirit throughout the 5K Makahiki Challenge.

"It’s self-paced, with music and people running around in costumes, so we didn’t go to really charge," he said.

The couple, who ran the Makahiki again in January, have signed up the whole family for the 5K Hawaii Aloha Stadium Sprint, a local version of the popular Spartan races that are held across the country. It will take place Sunday at Aloha Stadium and includes a children’s run.

For much of the week, the demands of work and school keep them in separate households where they’re raising children from previous marriages — Van Gieson in Nanakuli with his daughter Lilinoe, 15, and son Makoa, 11, and Lee in Kahala with her 11-year-old daughter, Lilly.

Because being a close-knit family is their top priority, they don’t view physical distance and juggling schedules as obstacles. Instead, they look for activities they can do together, such as the Spartan event.

The couple’s recent morning workout started with jogging in the sand. They also did crunches for core strength. To prepare for the race, burpees — jumping up from a prone position with arms overhead — would help them leap over walls and perhaps the fire pits of Spartan lore. Mountain climbers — running in place while bent-over with hands on the sand — oiled their joints for competitive crawling.

Water circuits followed, with Van Gieson paddling his racing canoe and Lee performing pushups, crunches, squats, planks and the yoga move upward dog on her standup paddleboard. "When doing workouts on the water, it’s an unstable feeling with the waves and currents, and you definitely have to engage more of your core," she said.

As a child growing up in Waikiki, Lee, a former lifeguard who’s now pursuing a nursing degree, did beach workouts with her paddler dad. It’s a tradition she and Van Gieson continue with their family.

"The children all play sports, so they connect fitness with play," she said. "That’s the best way to change everybody’s mind about working out."

"Training for life," Van Gieson added with a smile.

Come Sunday, when Aloha Stadium becomes Thermopylae for a day, the couple just might teach the Spartans something new.

"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. E-mail features@staradvertiser.com.