On land I’m a diligent exerciser who hits the gym regularly.

Onboard I have countless reasons for not working out. My yoga mat won’t fit on the deck. There’s a coffee and book in the cockpit calling my name. Happy hour got in the way.

But I didn’t bother telling any of it to Lisa and Myles Magnuson. I knew that wouldn’t fly with them. The Magnusons make it their business—literally—to tell people how to get buff onboard. The husband and wife, who are speaking at the Seattle Boat Show this week, founded Onboard Fitness in 2008 to teach people how to exercise on their boats.

The company emerged out of work that Myles, a personal trainer, was doing with clients. Some of his clients have yachts and would be out boating for extended periods, then return to the gym carrying more than just pleasant cruising memories.

“They’d be gone for months at a time and come back somewhat out of shape, so I just started creating programs for them,” Myles says. “I kept creating workouts they could do with limited equipment and space and that’s how it took off.”

Clearly, these energetic 31-year-olds, who live in Newcastle east of Lake Washington, aren’t your typical couch puppies. On their website, Myles describes his ideal day as involving fly fishing, reliving his collegiate lacrosse career and skiing down a mountain, followed by some sailing on Puget Sound. Lisa has been a boater since childhood, previously taught spinning and Pilates and now takes care of the couple’s seven-month-old daughter, Anya.

The Magnusons see their business venture as a way to combine their two passions, fitness and boating. Future plans for the company include ramping up their online store, which sells compact, easy-to-store equipment, and producing an exercise DVD, likely this spring.

While the Magnusons acknowledge that working out regularly takes discipline, particularly on a boat, they say boats offer more possibilities for easy workouts than people might realize.

For example, Lisa says, the countertop in a galley can be used for modified push-ups, or you can plant your feet on one counter and your hands on the opposite one, face-up, and do tricep dips. Resistance bands can be wrapped around places such as handrails or the mast, and if there’s enough room on the deck, it can be used for skipping rope and doing other exercises.

“The amount of exercises you can do in a small space is amazing,” Lisa says. “It’s just knowing how to do them, which is what most people don’t know.”

The couple demonstrates a few of those exercises in this promotional video they produced:

Recognizing the space constraints onboard, the couple focuses on exercises that can be done in a space about the size of a yoga mat. The minimum boat size needed for onboard exercises, the couple says, is around 27 to 30 feet. They speak from experience: their boat is a 27-foot Catalina.

The Magnusons say exercising on a boat is important for more reasons than just overall health—it also helps extend a person’s ability to sail later in life. Taking a cue from the world of pro sports, they create exercises intended to mimic the movements and muscle use involved in various boat activities, such as jumping off a dock and pulling lines.

“Exercise is basically practice for everything you want to be able to do,” Myles says. “Athletes are accustomed to that reason for training: they train for their sport. But the regular person is trying to do exercise, for the most part, just to look good. They’re not thinking that it’s important for them to practice the movements that they do all day long, because that’s what’s going to sustain your body for that activity.

“If you want to continue boating, you need to be fit so you can continue to do it into your 70s and 80s,” he says. “That’s one of the main drivers we hope to instill in people.”

But in an age when spending long hours sweating on mechanized machines indoors has become the fitness norm, Myles says people simply don’t think of boats as places for exercise.

“A lot of people are really accustomed to working out in a place that is meant for working out, but not a place that’s for recreation, like a boat,” he says. “You can utilize those two things together and create a fun workout on something that you’re enjoying your time on, as opposed to dreading going to the gym to work out.

“You can work out anywhere with very little equipment and just your body weight and get a good workout,” he points out. “It kind of takes the excuse out of people not being able to work out.”

He’s absolutely right. I’m going to get right on that—as soon as I finish my martini.

Lisa and Myles Magnuson will be speaking about onboard fitness at the Seattle Boat Show today, Feb. 1 at 4:15 p.m. and on Saturday, Feb. 6 at 12:15 p.m. Both seminars will take place on the red stage at Qwest Field Event Center and are free. For additional information, check the boat show website.