Jamie McDonald’s red cape flutters behind him as he trots down a sun-scorched, two-lane highway toward the small West Texas town of Iraan.

A truck hauling a mobile home kicks up a gust of dusty wind, 18-wheelers whiz past, and someone blows a car horn, wondering why a skinny guy pushing a baby jogger filled with supplies is ambling through the desert on a hot fall day.

If you’ve got a minute, he’ll fill you in.

McDonald, a 31-year-old Brit with an unshaven chin and a semi-permanent sheen of sweat, is running across the United States to raise money for children’s hospitals. He wears the cape (he’s got a grand sense of humor, too) because he calls himself Adventureman, and he says he wants to give back to hospitals like the one that helped him recover after he was diagnosed as a child with a rare spinal condition called syringomyelia.

McDonald expects to pass through Austin on or about Oct. 16. This night, though, he’s sleeping at the Mesa View Inn in Iraan, a luxurious break from his usual ritual of popping up a tent at a truck stop or coiling his lanky figure onto a park bench.

The miles since he left Cape Alava, Wash., on April 10 haven’t come easy.

“Just getting up every single day and having to go again is tough,” he says. “I’m at the stage that (my run) needs to be making a difference, and if I don’t feel like it is, I lose hope. That takes you to a whole new level of motivation. It has to be a bigger purpose than yourself.”

Sometimes, when it’s hot, McDonald runs at night, using a headlamp to carve out a tunnel of light. Once, he encountered a swarm of migrating tarantulas crossing the highway.

His route has taken him south to Los Angeles, east to Phoenix and on to El Paso. He dashed along Interstate 10 to Fort Stockton, then broke a little north, where he’s now discovering a string of rural communities along U.S. 190.

“Without a doubt, the biggest challenge has been running through the desert the past three months,” he says.

He runs about seven or eight hours most days, covering about 26 miles at a time. His biggest fear is getting hit by a car. He doesn’t care how fast — or slow — he goes each day, as long as he makes it to West Quoddy Head Lighthouse in Maine, the easternmost point of the continental United States, in early April 2019.

“I want to run free,” he says. “I don’t want to worry about time.”

As a child, McDonald, who lives in Gloucester, in the United Kingdom, struggled to walk. Doctors told his family he’d need to use a wheelchair. His mom encouraged him to keep moving, and he did everything he could to stay active. Slowly, the symptoms disappeared.

Seven years ago, on the brink of using money he’d saved to purchase a home, he felt the draw of adventure. He couldn’t settle down; he had to find a way to give back after rebounding from his health crisis.

He bought a cheap bicycle and decided to pedal 14,000 miles from Bangkok, Thailand, to Gloucester, England, to raise money to benefit the hospital that treated him. It took 10 months, and he raised the equivalent of about $15,000 for charity.

Determined to keep the momentum (and fitness he’d built) going, he then attempted to break the Guinness World Record for the longest ride on a stationary bicycle. He did that, too, with a 276-hour ride peppered with five-minute breaks.

Even then, he felt like he hadn’t finished. “Everyone in Gloucester said, ‘You should keep doing this stuff.’ It must have been pounded in my brain. Sitting on my parents’ toilet one day, I thought, 'Maybe I should keep doing this.' I jumped up and said, ‘Mom, Dad, I’m going to run across Canada.'”

Although he’d only ever run a single marathon (“and it was horrific,” he says), McDonald then made a 5,000-mile solo ride across the vast, chilly stretch of land between St. John’s, Newfoundland, and Vancouver, British Columbia. He ran through snow and frigid temperatures, grinding the tread off 13 pairs of shoes and losing the tip of his nose to frostbite. He got mugged, encountered bears and inspired the creation of a support group called Stalking Mamabears, which arranged a roadside candlelight dinner one night with a blind date.

Mostly, though, his inspiration came from parents of children with terminal diseases. By the time he finished, he had raised half a million dollars for children’s services and wrote a book about the experience, titled “Adventureman: Anyone Can Be a Superhero.”

He also set up an organization called the Superhero Foundation (superherofoundation.org) that provides grants to help families fund treatment for ill children. McDonald also earns money through motivational speaking.

With the Canadian run behind him, he geared up again this year with a run across the United States. By the time he finishes, he’ll have completed the equivalent of about 230 marathons.

He pushes a stroller carrying a tent, sleeping bag, food and water. He eats mainly sardines, peanut butter, beef jerky and nuts. And yes, he’s lost weight.

Two days into the adventure, he laced up his shoes, stood up and nearly fell down. “I’ve never felt a shooting pain like it,” he says. “I had plantar fasciitis.”

He realized, though, that it didn’t hurt when he wasn’t wearing shoes. He ran barefoot to the nearest hardware store, where he bought a pair of neoprene booties, which he used for the first 300 miles of his trip. (More recently, he’s alternated between minimalist shoes and support shoes.)

“It’s not boring," he says. "No adventure is boring, because every day is different. I don’t know who I’m going to see or who I’m going to meet. I spend most of my time in fight or flight because I’m on my own. That’s not necessarily a bad thing. It’s a place of growth and steep learning, and you become a better person for it,” he says

Money donated to McDonald’s campaign is distributed to local charities. In Texas, proceeds will benefit uninsured children who seek treatment at Texas Children’s Hospital in Houston.

And McDonald is already brewing up the next adventure. It’s a big one, and it doesn’t involve cycling or running. It involves his girlfriend, Anna McNuff, a fellow adventurer who recently cycled all 50 states in America and wrote a book about the experience called “50 Shades of the USA.”

“Babies,” McDonald says. “We’re going to have adventure babies.”