But a bristling Gallen has dismissed concerns over his long-term welfare ahead of a heavyweight showdown in Sydney with fellow former NRL great Nelson Asofa-Solomona.
At 45, Gallen will return to the ring on Friday week for his 20th professional bout, 16 months after first emerging from retirement to settle a decade-long score with Sonny Bill Williams.
As more and more retired league stars learn they are suffering serious brain damage from repeated head knocks, Anne Gallen naturally worries about her husband.
Gallen is promising this will be the last time he enters the ring after reluctantly accepting another massive pay day to fight the "Big Nasty".
"Nah, she's not happy. She's not happy at all," the father of four told AAP when asked what his wife thought.
"But it's my job as a bloke. It's my role in the relationship. I provide for my family. I'm going to give my family a life I never had and that's my sole motivation.
"That's what I'm here for: to look after them and that's what I'm going to do."
Cronulla's only premiership-winning captain and one-time NSW State of Origin series-winning skipper revealed he'd had a battery of brain scans over the years.
"I've done everything I can to ensure I'm in a good spot," he said.
"See, people talk about CTE. I've heard former footy players talk about it. But you do not know you've got CTE until you're dead.
"So, look, unless technology's changed in the past six months since I was last tested ... I'm not a doctor, so I don't know for sure but, as far as I know, people say they've got CTE are just making stuff up because you do not know you've got COT till you're dead.
"I've been told that by a professor. That's what I was told about less than a year ago. They can't tell until they cut your brain open."
Gallen is actually livid that Asofa-Solomona continually called him out, saying he was instrumental in helping the ex-Melbourne Storm enforcer and New Zealand international get a start with No Limit Boxing.
Now he wants retribution after claiming Asofa-Solomona broke the mateship code and landed too many verbal low blows.
"I told him I was done. I told him I was finished," Gallen said.
"He wasn't calling out Curtis Scott. He's not calling out Junior Paulo. They're footy players. They're younger. I'm 45. He keeps bringing up my name after the fact because he knows I didn't want to do this anymore.
"I'm going to smash his face in."
Then, he's promised his Mrs, he truly will be done.
"This is the third time I'm coming out of retirement now. Hopefully I get through this one and hope no one else calls me out," Gallen said.
"I've been tested, I've been scanned. There's no way a doctor's going to say, 'yeah, you can still fight'.
"I've been told I'm in a good spot and after this fight I'll get tested again."
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