"We immediately understood the seriousness of the situation, so responding with urgency was front of mind for us all," Mr Warena said. "The procedures we followed kicked in automatically because of our training. We knew our job was to try and save a life and we went about doing that as best we could.
"We were fortunate with the timing as the pool was quiet, ahead of the after-school rush. We had a full complement of lifeguards on duty as we were in the transition period between shifts."
Three rounds of CPR were given before the man started breathing. He was put into the recovery position and given oxygen to help breathe.
"I've been at the aquatic centre a long time and have been involved in many first aid and medical incidents," said Mr Warena. "I've been part of resuscitations before, in a support role, but this was the first time I've had to get someone breathing again."
The man was at the pool with two other people. It was his first time at the centre but he has told staff he wants to return to the pool once he has recovered.
"We were delighted to get a visit from the man and his parents earlier this week - his first day out of hospital," said service manager Noel Gulliver.
"He has no recollection of the event ... He and his parents expressed their appreciation to our team ... It was quite a special moment to meet him again, and to know that out team had played a part in saving his life."