The mother said after two days her son, who has "a loving wife and four wonderful children" was transferred to Waikato Hospital's intensive care unit but he was now
"starting to mend slowly" in a stroke ward at Waikato Hospital.
She also paid tribute to the lifeguards for looking after her son's dog and keeping track of his belongings, saying this was such a "wonderful help" to the family.
"No words can express all I want to say, so I will simply say -THANK YOU - from a very, very, grateful mother," the woman said.
According to the Facebook post, the lifeguards were at the beach setting up for the BP IRB North Island Championships when the man suffered the stroke in the surf.
"We're so proud that even when they were focused on another task, they still noticed this person needed help and sprang into action," the post reads.
❤️ 💛 The team at Waihi Beach Surf Lifesaving Club recently had this heart-warming note sent to them after they performed...
Posted by Surf Life Saving New Zealand on Thursday, 21 February 2019
"No doubt they gave this person the best chance of recovery and another example of surf lifeguards being such valuable assets to their communities, even outside of patrol hours."
Mark Vivian, chief executive officer of Stroke Foundation NZ, said: "We'd really like to add a huge thank you to the surf team for their awareness and swift action – undoubtedly, they will have made a huge difference in this case."
"Without their quick thinking, a family might have lost a son, a father, a husband. We'd like to wish the family all the best and of course, we are here to help in any way we can.
"Responding quickly is the best thing you can do if you think someone has had a stroke. The quicker you get them to a hospital, the better their chances of walking out," he said.
Vivan encouraged everyone to learn the FAST message signs– Face drooping, Arm weakness, Speech difficulty, and Take action call 111.
"It could save your life or that of someone you love," he said.
