Twice convicted of the 1992 rape and murder of Susan Burdett, he spent 21 years in jail. His convictions were quashed in March by the Privy Council, which recommended that he not be put on trial again.
Boxing will be a different challenge for Mr Pora, who played league in jail for the Paremoremo Raiders and who, aged 13, was good enough to represent Auckland East in the 1988 Roller Mills rugby competition.
A team photo shows him beside Pita Alatini, who went on to play for the All Blacks. When that photo was published in the Herald in 2013, he says, it gave him credibility with prisoners who couldn't believe he'd rubbed shoulders with an All Black.
In prison he used makeshift boxing bags. "We cut up our mattresses. We used to use the mattress and socks [for gloves]."
Mr Pora says he forgives the police officers who charged him.
He spoke of the emotion of hearing that he would not be put on trial again. "I got a phone call from Tim [McKinnel, private investigator] just telling me no retrial. I stopped the car; just me and my dog. It would probably be the first ever time, tears just running from my eyes, man."
"I went to the beach, Mission Bay, and just let everything wash out of the soles of my feet. Life began for me then."
Mr Pora celebrates his 40th birthday next month. It will be a double celebration - it is just over a year since his release from prison.
He was shocked when police charged him with Ms Burdett's rape and murder back in 1993, he says. "I couldn't believe they charged me."
Asked what he'd say to those officers, he doesn't hesitate, "I forgive yous, man, and just move on. Back then I had all the anger towards them. I understand the word forgiveness. It will put you at peace. You don't have to carry any more shit any more."
The charges were laid after he was interviewed for four days. Two juries judged him guilty before the Privy Council ruled that: "The combination of Pora's frequently contradictory and often implausible confessions and the recent diagnosis of his FASD [fetal alcohol spectrum disorder] leads to only one possible conclusion and that is that the reliance on his confessions gives rise to a risk of a miscarriage of justice."
At a family gathering soon after he was freed on parole last year, Mr Pora told relatives who had claimed he was involved in Ms Burdett's murder that he forgave them.
"I've never met Susan," he told the Herald. "I didn't know her from a bar of soap."
Nor had he met Malcolm Rewa, a lone-wolf serial rapist with the embarrassing affliction of erectile dysfunction, whose semen was in Ms Burdett's body. Rewa was convicted of rape but two juries could not decide whether he murdered her.
Read more:
• Phil Taylor: Malcolm Rewa must go on trial for murder
• 'Teina Pora was a red herring' - Susan Burdett's brother
• How the justice system failed Teina Pora
Of his confessions, Mr Pora, who was 17, said he was young and confused. "It was like getting interrogated ... I just said whatever they were saying. I just said 'yes' and said 'no'. I thought no was yes and yes was no back then. I just went along with it."
Prison was "a living nightmare".
"I was in amongst some of the most notorious criminals in New Zealand. Some scary shit there." Standing up to daily taunts of "rapist" and "murderer" sometimes led to fights, "and you can't win them all".
For the first two years he marked time, keeping note of each passing day. "And you just get sick of it. It was slowing down everything."
Years passed between visitors.
"As the years went on I just started to realise no one cared, so I might as well live the lifestyle of being in prison, the art and craft of being in there."
Everything changed 11 years ago, he says, when he was baptised by a fellow inmate using water from a prison laundry tub.
He taught himself to read using a pocket Bible. "I'm a different person now. Humble. In the past I'd have been, yeah, aggressive."
He'd lost his anger and his attitude. "I don't have anything towards anyone any more."
Religion changed him and Mr McKinnel saved him. When the former detective, whose work led to his convictions being quashed, turned up five years ago, Mr Pora was initially wary.
"I was in the exercise yard when I got a phone call. A Tim from Hawkes Bay? He just asked me, said he was interested in my case. I just hanged up the phone and the next day he was there. Unbelievable.
"Without Tim ... I'd still be sitting behind those four walls."
• Watch the full video interview with Teina Pora here.
• How did the NZ justice system fail Teina Pora? Phil Taylor takes an in-depth look here.