Sandra Billinger, an assistant professor of physical therapy at the KU Medical Center, and her son, Michael Thomas, 20, have been trekking across Kansas at about 25 miles a day. Wednesday night they stayed at Clinton Lake then left, hoping to reach Kansas City by Friday. The pair are raising awareness and money for stroke research.

Walking across the state of Kansas in about three weeks isn’t easy: You’ll get blisters, your feet will ache endlessly and you may find yourself covered in ticks after hiking through tallgrass prairie.

But as a physical therapist, Sandra Billinger knows it’s hard for survivors of stroke to walk, too.

“In rehab, we ask them to do a lot of hard, difficult things,” said Billinger, an assistant professor of physical therapy and rehabilitation science at the Kansas University Medical Center.

Billinger passed through Lawrence on Wednesday near the end of a 23-day walk across Kansas. She and her 20-year-old son, Michael Thomas, are making the 570-mile trek, at a clip of about 25 miles per day, in an effort to raise funds for new equipment to research the benefits of exercise for stroke survivors.

That’s the primary purpose of their journey, but it was a mix of different inspirations that made it happen.

The idea came from an offhand suggestion from Thomas, as they tried to think of something to do to mark the finish of his classes at Johnson County Community College and his transfer to Fort Hays State University.

“He said, ‘Maybe we should walk across the state,’ ” Billinger said. “He was kind of joking.”

But Billinger noticed that May was Stroke Awareness Month. And her research lab focuses on the benefits of physical activity for survivors of stroke, beginning as soon as within 24 hours of the incident. What better way to promote that exercise, and attempt to raise money for some equipment to examine brain blood flow and better understand its benefits, than a walk across Kansas?

Also coming up in late May was Thomas’ 20th birthday, which coincides with the anniversary of the life-changing event that led to Billinger’s career in physical therapy.

Back in 1993, when she was working as a dental assistant in her hometown of Hays, Billinger had a serious car accident. It led to seizures, caused spinal nerve damage and other injuries and forced an emergency Caesarean section to deliver her son — Michael — after she went into early labor. After a lengthy recovery, she was left with no feeling in her right hand, unable to safely handle dental tools. So, as a single mom with two kids, she decided to go back to school, and become a physical therapist.

By 2008, she had earned her Ph.D. from the KU Med Center, and she became a professor.

So 20 years after she and Michael had gone through that journey, it seemed right to go on another one.

They began their walk May 16 on the state’s western edge, roughly following the path of the old Santa Fe Trail.

“It’s a very simplistic life, you know?” Thomas said in a phone interview earlier this week. “You just kind of wake up, eat breakfast, pack up, start walking.”

Billinger and Thomas had hiked before, and they prepared with some long weekend walks this spring. But they weren’t quite ready for this.

“Nothing, I think, can really prepare you,” Billinger said.

The foot pain is unending, they said. By the second day, Thomas had developed a painful two-inch-long blister that he popped, glued shut and felt with every step.

“It was excruciating,” Thomas said. “I was not a happy camper that day.” Billinger said she had her “meltdown” earlier this week, when she discovered she was covered with about 30 ticks as they walked through the Flint Hills.

But they’ve learned a bit of history about the pioneers who traveled across the state years ago, and enjoyed the kindness of strangers who gave them fresh food in place of the dehydrated meals they’d packed.

“The people of Kansas have been so thoughtful,” Billinger said.

They’re set to reach their destination, the KUMC campus in Kansas City, Kan., on Friday. Billinger said she expects to have raised $20,000 toward their $50,000 goal by then. To donate, or to sign up to walk alongside Billinger and Thomas during their final stretch, people can visit walkacrosskansas.com.

When they’re done walking, Thomas will head to FHSU with hopes to become a sports rehabilitation therapist. And Billinger will return to her research. But first, she has her plans set for Saturday: Do absolutely nothing.