Mark Matheson is sleeping on his chest half the night to toughen himself up.

On Sunday he’s going to be chest-down on a paddleboard for maybe 10 hours, and he’s been working hard to get ready.

On Tuesdays he spends an hour to 90 minutes paddling from Wailupe to Hawaii Kai. On Thursdays he does wind sprints.

Then on Saturdays it’s a five-hour solo paddle. He’s been doing this for more than a year in preparation for the Molokai 2 Oahu World Championship Paddleboard Race on Sunday. He will be the first athlete with paraplegia to compete in the 32-mile crossing of the Kaiwi Channel.

"I’ll tell the other guys, ‘Be my Motel 6. Leave the light on for me. You guys go head. I’ll chase you the whole way.’"

Matheson, a 48-year-old executive with defense contractor Science Applications International Corp., was injured in 1993 when he fell off a fourth-floor hotel balcony on Kauai. The paralysis starts at his sternum.

He grew up surfing in San Diego, and when he hooked up with Access Surf Hawaii, an agency that supports adaptive water sports, he got back on the waves.

He entered the Duke’s Ocean Fest paddleboard competition last year.

"People were saying I was the first paraplegic to complete the race, but that’s not that big a deal." The Molokai 2 Oahu was the next challenge. It is a big deal, but Matheson isn’t eager for media attention.

"It should be about the organizations and their missions. And that I said thank you to my wife."

He’s dedicating his race to Easter Seals Hawaii and Access Surf, asking people to go to either group’s website and make a donation. "Maybe a buck a mile, even 10 cents," he said.

His goal is to raise more than $25,000 for both nonprofit groups. Matheson has been on the board of Easter Seals for four years and is its board president. He has been active with Access Surf as well, and would like to help them buy equipment such as balloon-tire wheelchairs.

In preparation for the paddleboard race, Matheson went to Molokai to scope out the beach where the race starts. On training runs his buddies carry him across the sand to the ocean or help him bring his wheelchair down a boat ramp so he can get on the board. On Sunday an escort boat from Access Surf will accompany him. His wife, Stacie, will see him off on Molokai and then bring his regular wheelchair and his beach wheelchair back to Oahu on the plane.

"Make sure you write that I said thank you to my wife," he says.

His personal goal is to finish in under 10 hours, maybe even eight hours. "The good guys can do it in five hours," he said. But then he’ll meet his goal before the race even begins.

"In terms of measures of success, it’s being able to show up at the starting line, because it means I’ve put in the time training, planned the logistics and earned the credibility to at least start the race," he said.

After the race his friends and supporters plan a dinner at Roy’s Hawaii Kai across the beach from where the paddlers come on shore.

"For me this is like something to check off the list, so if somebody asks, ‘Hey, did you ever cross the Molokai channel?’ I can smile and go, ‘Yep.’"

Lee Cataluna can be reached at lcataluna@staradvertiser.com.