Keith Kennedy was found Sunday night without any clothes on, covered in dirt and ticks, and suffering from hypothermia and dehydration.
He also had gone days without medicine he's taken since having a kidney transplant in 1995.
But through all of that, doctors say he's improving and they're optimistic he'll pull through.
Keith Kennedy's parents say their son has always been a wanderer -- any open door or window was an invitation to explore.
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His mother Linda Kennedy says the question, "Where's Keith?" was probably the most common phrase heard in their home.
"From about age 3 he's been a runner, and our house, really, truly, was like Fort Knox. We had so many systems set up to make sure that he was safe and not going to escape," said Linda Kennedy.
He's been found before in stores and even a factory near the Kennedy home, but nothing ever like this.
The young man wandered away a week ago from the camp in Wisconsin he was attending for people with developmental disabilities.
One theory is his love for popcorn drew him back to the kitchen to sneak a snack, and he didn't go straight back to his cabin for fear of getting caught.
Hundreds of volunteers spent last week scouring at least 14 square miles before two firefighters found Kennedy in a heavily wooded area that no one thought Keith would ever go into, though it had been searched before.
Kennedy's father, Bruce, says it wouldn't be surprising for searchers to miss a target in that area the first time. He says he and his wife didn't even have confirmation their son was alive until the car ride out to the site.
"He really was filthy, and his eyes were glazed and he was moving slowly, but he was moving," said Bruce Kennedy. "He even attended to me when I spoke to him and looked at me even though, through glazed eyes, I knew he was hearing me and so forth. Considering the alternative, it was awesome."
Just why or how Keith disappeared will likely never truly be known. Keith's autism limits his vocabulary to four words.
That limit also hampers doctors, who rely on patients to tell them what hurts.
Even after checking and double-checking for injuries, University of Minnesota Dr. Timothy Whelan says Kennedy is doing great. His body temperature is back to normal after being below 90.
The ticks that covered Kennedy's body aren't the kind that carry Lyme disease. And his kidneys are still functioning, albeit poorly.
"We're all very hopeful the kidney's going to turn around," said Whelan. "I, personally, really think there's a very high likelihood that he's going to do tremendously well, but we just don't know. We have to wait a little bit more time, at least a few days."
Linda Kennedy says the happy ending makes the search an event everyone involved will always remember.
She's resolved to help out the next time she hears of a missing person, and she hopes the incident doesn't turn people off to these kinds of camps that she says truly do help people with disabilities.
Bruce Kennedy is also making changes. He says he's been researching GPS chips that can be implanted under the skin to track a person that's wandered away.