It was 1988, and Martin Pistorius was a healthy 12-year-old boy growing up in South Africa when his life took an unexpected turn. Pistorius went home from school with a sore throat, and he never returned.
His body gradually weakened. He lost the ability to walk, to eat on his own and eventually, the ability to communicate. Doctors suspected some kind of neurodegenerative disease, but his case was a medical mystery. Martin's parents say doctors told them their son now had the intelligence of a three-month-old, and that they should take him home to die.
The last words he ever spoke: "When home?"
But Pistorius didn't die. He spent more than a decade at home and in day-care centers. His parents were told he was unaware of the world around him, but about four years after he fell ill, Pistorius says he began to "wake up."
"For so many years, I was like a ghost. I could hear and see everything, but it was like I wasn't there. I was invisible," Pistorius told NBC News' Kate Snow with the help of a device that speaks the words he types into a computer.
"What really got to me was the complete and utter powerlessness," Pistorius said. "Every single aspect of your life is controlled and determined by someone else. They decide where you are, what you eat, whether you sit or lie down, in what position you lie in, everything."
Day after day, year after year, Pistorius was trapped in a body that wouldn't move, left with nothing but his own thoughts.
"I would literally live in my imagination," he said. "Sometimes to such an extent that I became almost oblivious to my surroundings."
His family struggled to come to terms with his illness. One night, after his parents argued, his mother turned to her son and said, "I hope you die." She didn't think her son was there to hear it, but he was.
"It broke my heart, in a way," Pistorius said. "But at the same time, particularly as I worked through all the emotions. I felt only love and compassion for my mother."
But in 2001, there was new hope. A therapist at Pistorius' care center, Virna Van Der Walt, began to pick up on tiny signals that made her realize he was more aware than people thought.
"He had a sparkle in his eye, I could see he was understanding me," Van Der Walt wrote to NBC News' Kate Snow.
She urged his parents to take him for cognitive testing, and for the first time, Pistorius was able to show people that he understood.
"She was the catalyst who changed everything," Pistorius said. "Had it not been for her, I would probably either be dead or forgotten in a care home somewhere."
As his mind grew stronger, so did his body. Pistorius was given special equipment he could use to communicate, which, he says, changed everything.
"I don't think I will ever forget that feeling when my mom asked me what I'd like for supper and I said, 'Spaghetti Bolognese,' and then she actually made that," he said. "I know that must seem insignificant, but for me, that was amazing."
Pistorius had to relearn everything - from reading and socializing to making decisions for himself. He went to college, learned to drive, and even feel in love.
He married Joanna, who he met through his sister, in 2009, and they are hoping to start a family.
"It took a massive amount of work, blood, sweat and tears," he said. "But I am a different person today that I was 13 years ago."
Today, Pistorius works as a web designer. His story captured in an autobiography, "Ghost Boy," is on The New York Times best-seller list.
He's grateful for the little things, like being able to have a conversation or experiencing something for the first time.
His message - don't overlook what's possible.
"Never underestimate the power of the mind, the importance of love and faith, and never stop dreaming," Pistorius said, adding one more piece of advice:
"Treat everyone with kindness, dignity, compassion and respect, irrespective of whether you think they understand or not."
This story originally appeared on NBC News on January 29, 2015.