Mayhew clarified that he did not have a heart attack, but a cardiac arrest.
"Basically a heart attack is when part of the heart muscle dies because of blockage in one of the coronary arteries, so a lot of heart attacks can cause cardiac arrests, but a cardiac arrest is basically when the heart stops and it can be caused by a number of things."
The Warriors doctor said his personal situation was due to a viral cardiomyopathy, where a virus had damaged the heart.
"In some ways you can say it's worse than a heart attack, because it's left some permanent damage to the heart and the pump - as I like to think of my heart - doesn't work as well. Subsequently I've had a defibrillator put in my chest to make sure if the same thing happens again I'll get a shock."
Mayhew said the incident pushed him to help out Heart Savers, an organisation dedicated to educating the public about AEDs - automated external defibrillators.
If the defibrillator had not been at his gym, Mayhew said he "most probably would have died".
"That sounds very dramatic, but the good thing now days is that people have been well trained, and we're trying to train everyone in the art of cardiac massage and resuscitation."
He said there were not enough defibrillators in New Zealand, but there were never too many.
"What I'm trying to do with Heart Savers is make an awareness to have more defibrillators around New Zealand, so if someone has the misfortune of what happened to me, the chance of survival is greatly increased."
Mayhew said he thinks defibrillators should be in every workplace, school and sports team training facility.
"I'm involved with the Warriors and we have them at our training venues... You could argue that the greatest risk of going to a Warriors game is someone in the crowd rather than the players, but we have [them] for both purposes."
The 60-year-old carried a defibrillator in the boot of his car.
"It's very, very easy to use. It's virtually self explanatory."
Mayhew said most AEDs would activate audible instructions when turned on to tell people what to do.
"A lot of companies now like Heart Savers educate people on how to use them, there's a number of dummy machines around you can try, it really talks the person through it."
Mayhew said he feels "incredibly lucky".
"When I woke up and spoke to [a psychologist] the hospital had organised, she said: 'Are you depressed or down?' And my overriding emotion was: 'How lucky am I?' I should have died, and I see everyday from here as a bonus and I'm very lucky."
He credits the quick actions of others for his survival, and "very good" treatment later on in hospital.
The Warriors' doctor said he wants to encourage involvement in the Heart Saver campaign, which is pushing for defibrillators in the community.
"I'd like people to take heed of the Heart Saver campaign that we want more defibrillators ... I've resuscitated a few people in my medical career, but I never thought I'd be at the other end of it. It can happen to anyone and good [outcomes] are improved by the easy availability of defibrillators and people who know what they're doing."
Heart Saver provides a full range of health and safety solutions, including AED supply.
The organisation is passionate about making AEDs more accessible to New Zealanders.
They believe the more AEDs they have around the country, the fewer deaths there will be.
