Renowned for his incredible stamina, Gallen managed just 25 minutes for his opening stint in the grand final, before returning again in the 47th minute.
However, quite remarkably, Gallen punched out 164 metres - surpassing his season-average of 163-metres - from a total of 19 runs in a total 59 minutes.
Gallen was an emotional wreck after the grand final siren, yet it seems nobody was aware of the physical toll the build-up of the past month, as he strived to become the Sharks' first premiership-winning captain, had taken on his body.
"At the end I thought I was going to pass out," Gallen said after the match.
"It's just an amazing feeling. We wanted it more than they did."
Gallen was admitted to hospital at 6.30am, before checking out to attend the Sharks fan day.
He was able to sign autographs and pose for photos for an army of fans who had gathered at Southern Cross Group Stadium to celebrate the historic victory on Monday, but quickly retreated back to his lounge room to rest at his home in Cronulla.
The remainder of his Cronulla teammates were planning to celebrate long and hard on Monday night.
Gallen was also the first player to leave the players, team officials and family function at the Sharkies Leagues Club, following the premiership win.
Eager to be part of Mal Meninga's Four Nations Australian squad which is named on Tuesday, Gallen told Sharks officials he would prefer to regain full health than risk further illness by celebrating the club's inaugural NRL title.
Man of the match in the Kangaroos' Anzac Test victory over New Zealand earlier this year, Gallen is hoping that Meninga's dressing room promise to stick with the same successful 17 that toppled the Kiwis for the Four Nations comes to fruition.
However, with injury and finals form uncertainty over Test incumbents Matt Scott, James Tamou, Josh McGuire and Sam Thaiday, there could be changes. Having conquered his final frontier by collecting a premiership-ring with Cronulla, Gallen would be considered unlucky not to be chosen.
