Brian Cunha went into cardiac arrest while on the walk.
A good Samaritan saw him collapse and performed CPR while they waited for 911.
According to Cunha, his heart stopped three times. He was in the hospital for four days.
Doctors told Cunha if that good Samaritan hadn't acted so quickly, he might not be alive today.
The good Samaritan also stayed and waited with Cunha's dog, Cooper, to make sure he didn't end up at the pound.
According to Andrea Fuller, a CPR-certified volunteer from the American Red Cross, they hear stories like this once a month and encourage people to brush up on CPR training.
"Even if you aren't fully trained, anyone in our communities can perform what's called hands-only CPR," she said. "Once you call 911, the operators on the 911 call will happily walk you through it. The great thing is that you can actually save lives."
Cunha has not had a chance to thank the good Samaritan in person, but says he's incredibly grateful.
"I'm just incredibly grateful," he said. "You saved my life. My nieces and nephews are grateful, my dog ... I owe my life to you, so thank you."