Jackson Cunningham lurches across the gym during a recess game, racing a fellow sixth-grader toward a doorstop tossed onto the floor. His right side is outstretched, but his left side trails behind -- a lingering effect of the paralysis he has endured since suffering a stroke in 2011.
The 11-year-old is beaten by an inch but heads back to the sidelines with a smile.
It is the same quiet determination he showed when pushing a more famous stroke victim -- a U.S. senator -- to conquer his own pain and doubts.
Jackson and Illinois Republican Mark Kirk have warmed hearts and inspired fellow stroke patients with their odd-couple friendship, an unlikely meeting of two distinct worlds -- one full of Legos and zombies, the other focused on Iran sanctions and immigration reform.
A visit to Jackson's school in this small central Illinois town and another to witness his grueling routine at the Rehabilitation Institute of Chicago demonstrated the spunk behind the boy's advice urging Kirk not to give up on himself.
"I feel just a little lucky, not having something more severe," said Jackson, who's been called on to share his own rehab story in hopes of inspiring other kids. The National Stroke Association estimates that strokes affect 6 out of 100,000 children.
He says he feels blessed "to be able to talk to a lot more people and give more advice."
Almost a year after Kirk returned to the Senate, Jackson carries on with his own rehabilitation, confronting typical concerns about plateauing and not getting more of his strength and motion back.
Jackson and his family live in Oakwood, a town of 1,500 surrounded by farms and fields in Vermilion County along the Indiana border. Father Craig Cunningham works on the assembly line at the local Quaker Oats factory. Mother Erin works in human resources for auto-parts maker ThyssenKrupp Presta at another nearby factory. Grandparents help shuttle Jackson and sister Jordyn to and from school.
Jackson's elementary school gives a sense of his local celebrity, with bulletin boards that prominently display news clippings of Jackson and Kirk smiling outside the Capitol.
Among his memories, Jackson now counts an episode in which Kirk allowed him to sneak into the vice president's chair in the Senate when security officers weren't looking.
After emerging from the foxhole of shock common for stroke victims, Jackson set an early goal to "get everything back" and began an exhaustive schedule of physical and occupational therapy.
News of Kirk's own ischemic stroke in February 2012 -- caused, like Jackson's, by a blood clot -- hit home with the Cunninghams. At a speech therapy session, Jackson's grandmother suggested the boy write Kirk a letter.
The senator and former naval reservist received thousands of get-well wishes, his staff said, but the note from a young stroke victim near Kirk's hometown of Champaign stood out. Letters soon were exchanged with increasing rapidity. Jackson updated the senator with milestones. Kirk nicknamed him "Little Cabbage."
Before long, Jackson was invited to meet Kirk at his townhome in the Chicago suburbs and later in Washington.
Kirk calls Jackson a "loyal and motivating force" and says his own road to recovery would have been even more challenging without the improbable friendship.
"His ability to stay positive and keep fighting without hesitation is what I keep in mind every day as I continue working," Kirk said.
Kirk kept Jackson in mind as he climbed the Capitol steps last January -- a public test of the senator's endurance as he returned to work.
"Congratulations!" Jackson wrote. "I felt very happy and emotional when I saw you on TV. I hope I get to climb those steps someday, too. When I watched you, it reminded me of when I walked to the Lego store when I was a patient at RIC."
The two often talk about zombies, video games and Kirk's ferocious black cat, Cleopatra. And the unfettered access to a member of the one of the world's most prestigious political bodies gave a personal history lesson to Jackson, who pulled up his grades and began enjoying school more.
The senator has offered his own motivational remarks when the boy became discouraged about his impairments.
"Jackson, I expect you'll do absolutely everything your doctors and (therapists) say," Kirk wrote in response to the boy's frustrations with not being able to play baseball. "And if you don't, you'll have to testify before the United States Senate."
The relationship fills a void for the boy whose struggle at times has isolated him from peers.
The senator and Jackson will sometimes "sit in a room, and maybe they won't say anything for 10 minutes," Craig Cunningham said. But when Jackson leaves, "he's relaxed."
"It's strange," Cunningham added, "just because they both kind of understand each other, even though there's such an age difference."
At a recent therapy session in Chicago, Jackson completes dozens of jumping jacks -- a feat he worked on all summer to bring his left and right sides into sync. Therapist Sheila Krahl marvels at how much stronger his core muscles have become in just a few months.
During the recess game at school, Jackson wore an electronic device that sends shocks to his left foot. Hidden under his sweatpants, it helps him with mobility.
In November, he completed the Rehabilitation Institute's annual SkyRise climb of all 103 floors of the Willis Tower in 48 minutes, besting the times of many adults. Kirk climbed too, completing 41 stories.
"He speaks to all these kids what determination is," teacher Nicole Johnson said. "And at the same time, he's just Jackson."