Story highlights A Colorado man who suffered cardiac arrest at a marathon found his first responders through social media

In his video, he urges people to learn CPR

(CNN) A Colorado man used a heartfelt Facebook video to find his first responders after collapsing at a half-marathon in Florida.

Amy Smythe, 39, of Newark, Delaware, could not stop thinking about the man who had collapsed nearby, mere feet from the finish line of the Key West Half Marathon last week. She had just set a personal record, beating her previous best by 20 minutes.

Amy Smythe, a nurse in a cardiovascular unit, helped another marathon runner.

"It was fate that I had finished early," she said.

Bill Amirault, 44, of Colorado Springs went into cardiac arrest as he was rounding the final corner of the race. Smythe, a nurse in the cardiovascular unit at Christiana Care's Christiana Hospital, wasted no time.

"I think my instincts just kicked in," Smythe said.

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