A Toronto police officer on the brink of death less than five months ago is attempting a big comeback.

Const. Andrew Rosbrook suffered a heart attack while running a half-marathon in May.  On Thursday he was back up and running again, this time with the woman and fellow officer who helped save his life.

"I was very, very lucky, very fortunate," Rosbrook told CBC News.

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Const. Andrew Rosbrook is running in the National Peace Officers' Memorial Run five months after he collapsed during a half marathon and was revived by Const. Laurie McCann. (CBC)

On the morning of May 5, Rosbrook, 47, collapsed face down on Lake Shore Boulevard at about the 20-kilometre mark while running in the Goodlife Fitness half marathon. He had no pulse and was not breathing.

For seven minutes, Rosbrook was clinically dead.

"When you're up towards seven minutes [without breathing], you get to that crucial time where things really start to shut down,” he said.  “You don’t get much closer than that.”

Near her spot where she was working a paid duty assignment at the marathon, Const. Laurie McCann heard a scream and ran to help.

"I go running over. I find Andrew and I flip him over," she said.

With the help of an off-duty doctor and another man, McCann performed CPR on Rosbrook. At the time, she did not now he was also a Toronto police officer. Paramedics soon arrived with a portable defibrillator.

"I put the pads on and the paramedics shocked him and got him back to life. Got him standing here today," she said.

Plaque buildup on one of Rosbrook’s arteries had triggered his heart attack.

He’s since been cleared by his cardiologist to return to return to running.

On Thursday, Rosbrook joined McCann — they are now good friends — in the National Peace Officers' Memorial Run to Remember. Devoted to officers who've died while on duty, the three-day relay race covers 460 kilometres from Toronto to Ottawa.

Rosbrook plans to complete 80 to 100 kilometres of that distance. He’s done the run three times before, but this time he’ll have McCann along as backup.

“I’ll be right beside him,” she told CBC News.

And for the first time in the race’s history, the same portable defibrillators that helped save Rosbrook's life back will be available along the route, provided by the Mikey Network.