But their dream Sunday outing turned to tragedy when four of the group decided to end their day with a swim at the rugged coastal beach on Auckland's west coast.
Fai's younger brother got separated from the group of four who jumped into the water, and got into difficulty.
He got caught in a rip and Fai jumped in to try to save his brother. The other three made it back to the beach unharmed, but Fai was swept away.
He has not been seen since about 8pm on Sunday and is presumed drowned.
His girlfriend Jenna Frost, a 2007 Miss Samoa New Zealand contestant, watched Fai's rescue efforts.
She said it was heart-wrenching and she felt totally helpless as she watched the waves sweeping him away.
"I felt like I wanted to jump in there to get him myself'," said Ms Frost.
Fai's uncle, Puna Asalele, said the rugby league player had gone to his aunt's house on Sunday afternoon when his cousins started asking him how the Warriors trained.
"Like Sonny, his cousins are all Warriors fans and was thrilled when he told them that he will take them out to Bethells Beach to show them," Mr Asalele said.
"I was totally shocked when I received a phone call from Sonny's mother that night to say he was swept out to sea."
Mr Asalele said it had always been Sonny Fai's dream to play for the Warriors.
He had been a fan "ever since he was a kid".
Surf Life Saving NZ spokesman Dean Storey said a member of the public alerted an off-duty lifeguard that four men had been swept out to sea.
The conditions were rough, with a 1.5m swell, and two inflatable boats and a Westpac Rescue Helicopter had been used in the search for Fai.
His sister, Lalelei Fai, said family members had searched the beach until 2am yesterday, when they were told to go home, but returned at 5am to find that others from the Warriors had already started scouring the coastline.
Ms Fai said Sonny Fai was someone who always put others before himself, and described him as her parents' right-hand man.
"I wish that it was me, and not him, that had gone missing," said a tearful Ms Fai.
She said the extra training session he made on the beach on Sunday ahead of the Warriors' first training session of the season, which was scheduled to start yesterday morning, was typical of his "hard work ethic".
The Warriors did not train yesterday.
The entire 40-strong squad, including team manager Don Mann and former All Blacks coach John Hart, joined the family and church members in a massive search for their missing mate.
Mr Mann said the players were devastated when they learned Fai was missing, and the team paid for a helicopter to conduct an aerial search across the vast coastline.
A police boat was also used in the search yesterday, until it was called off at 1pm due to a change in the tide.
A former coach of Fai last night paid tribute to "a humble kind of person who never talks himself up and is always willing to put others first".
Others spoke of a kind-hearted man and the rock of his family who rarely missed a day of church.
Fai's Mangere East Hawks coach Roy Chan, said Fai was your typical Polynesian kid.
"I heard he went to help someone out before he went missing, that's just typical Sonny."
Yesterday, members of the Samoan Methodist Church in Otahuhu congregation helped with the search or prayed for their friend and relative.
Family and friends, although distraught, refused yesterday to give up hope that Fai will be found alive.
The search will resume at first light today.
