That was 31 years ago, the day two strangers who knew CPR saved Nilson's life.
"I would not have survived. They kept me alive until firefighters arrived," Nilson said. "It was an experience that would profoundly change my life forever."
That near-death experience would eventually help Nilson realize that his calling would be to become a firefighter.
Today, he's got 22 years of experience responding to fires, accidents and medical calls. He proud to work for Central Kitsap Fire and Rescue.
"It didn't happen right away. I took years to figure out what path I would take," he said. "But once I knew, I thought, what a great privilege... to help those who can't help themselves. I love it."
He has made teaching CPR a mission, becoming one of the leading instructors in the state, and working to provide free classes to the public.
Nilson was at a baseball game with his family in Everett on a July day in 1983 when he took shelter beneath a tree while holding his brother's umbrella.
He thought he had been hit by a car, but when he regained consciousness and could speak with his family, they told him he'd been hit by lightning.
Today he and other firefighters showed children how to perform CPR at Central Kitsap Fire and Rescue's Kids Day at the Kitsap County Fairgrounds.
Nilson realizes young children generally would not have the strength to handle CPR in an emergency, but he hopes exposing them to the life-saving technique now will motivate them to take a class later.
And, he points out, every child has a parent. Nilson wants to spread his message and pass along his skills to as many people as possible.
He says he often begins his CPR classes with a question.
"I'll ask them, who here has done CPR? Who has known a CPR survivor? And often times nobody raises their hand," he explains. "At that point in time I tell them 'Hi, my name is Ken Nilson, I'm a CPR survivor and you've now met one, and now I'm going to teach your class.' And I thank them for coming and learning the skill, because they could be saving my life again.