Motu says the painful injury had happened six weeks before the fight against Walters, when the pocket-sized Peach Boxing star had been sparring heavyweight duo Lani Daniels and Alrie Meleisea.
“I must have happened because they’re heavyweights and they’re strong, and I forget how little I am.
“I knew there was something going on, but I just blocked it out because I was so determined. I didn’t want anything stopping me getting in that ring.
“I could definitely feel it in the fight but I just kept thinking, ‘nothing beats childbirth’. That’s why I just told myself shut up, don’t cry or complain because that’s way worse.”
When Motu says she didn’t complain, she means it.
Even coach Isaac Peach didn’t find out until a week after the fight, while on holiday in Fiji.
Understandably, Peach was not best pleased Motu had kept the issue to herself and, looking back, she admits it wasn’t her best move.
“I’ve learned I need be a lot smarter and speak to my coach about those things because we can find methods of working around them.
“I’m being a lot smarter and more clever about looking after my body. Recovery is really important, which I’ve neglected.”
It’s not just Motu’s body that’s in better shape this time around, either.
New Zealand’s latest boxing world champion’s profile skyrocketed in the build-up to her fight for the vacant title, creating a level of demand on her time she’d never experienced.
The media requests have continued to roll in during recent moments, while speaking engagements around the country have also been added to the list.
Mentally, though, Motu feels fresher and more focused for her maiden title defence.
“Now that I’ve let go of everything and I’m just growing, now I can focus on just being the fighter.
“I feel amazing, and I feel at peace with myself.”
They’re all good signs that another victory could well be on the cards at Eventfinda Stadium on Saturday night.
A win would not only extend Motu’s pro record to 17-0, but send a message to the other title-holders and big names in her division.
“I’m just determined to fight - I love jumping in that ring, and I’d love to fight them all.
“I’m not hiding, I’m right here.”