On the morning of July 18, 2004, Pete Koutrakos got ready for work while his wife, Jennifer, slept soundly. Pete headed into the garage and got into his car to hit the road, but there was a problem. The car wouldn't start.

Using the nearby jumper cables, Pete used Jennifer's car to start his own. It worked, and Pete drove into work like he had so many days before.

But this day would be different. Pete made one fateful mistake before he left the house that morning: He closed the garage door but forgot to shut off Jennifer's car.

While Jennifer slept, carbon monoxide fumes filled the house.

When Pete hadn't heard from his wife by that afternoon, he grew concerned. After his calls to the house went unanswered, Pete raced home to an unimaginable scene. His wife and their two dogs were dead. The carbon monoxide fumes had killed them all.

Courtesy of Pete Koutrakos Jennifer and Pete had been married for a year and 10 months (together for nine and a half) when she died.

Four months after the tragedy, Pete appeared on "The Oprah Winfrey Show." His grief and emotions were still raw as he spoke of the guilt he carried over the death of his wife and pets.

"It was a split second of forgetting," he said back then. "Initially, you blame yourself. It's like, 'Why didn't I shut the car off? Why didn't I shut the car off?' You go, 'Why?' and you can't do that. You can't 'Why? Why?' all the time. You'll go nuts."

Pete's heartache was palpable to the audience that day as he opened up about the tragic mistake, and Oprah later explained that there actually were several layers to this lesson.

"On the surface, it looks like, 'Oh, a lesson about carbon monoxide poisoning,' and it looks like a lesson about leaving the car on in the garage," she said. "But it really is about present moment. This present moment, and staying in the consciousness of this present moment."

Pete has since said that appearing on "The Oprah Winfrey Show" back then helped him heal, adding that the support and kindness from strangers is what keeps him going.

Another heartrending lesson: