The former New Zealand Colts midfield back had to quit the game at 26 due to a degenerative knee problem.
Naufahu, 41, who played Khal Moro in the sixth series of Game of Thrones, was playing for Glasgow in the Celtic League when forced to retire.
The one-time Southland and Canterbury representative told BBC Scotland he struggled to adjust without rugby in his life.
To fill the void he turned to weightlifting, returning to New Zealand to work on construction sites before opening a gym in Auckland.
"When you can't play anymore, you don't feel like you're enough, you don't want to go to the gym," he said.
"I'd done a little acting as a teen. At the time, there weren't many Polynesian actors in New Zealand, so I got a small part when I was injured.
"I never went to formal drama school or whatever. But what acting did was give me a creative outlet which had been closed when I lost the ability to play rugby."
Naufahu likened playing in Game of Thrones and getting "flown around the world" was "like a rugby team - the Dothraki rugby team. We had guys from England, France, Brazil - all good guys. No egos, no-one above anyone else."
Naufahu made his mark in rugby at Auckland's King's College in the mid-1990s and was named in the New Zealand Colts in 1998.
Signed by the Canterbury Rugby Union academy, he played in pre-season games for the Crusaders in 1998 and was on the fringes of their Super Rugby squad in the early 2000s.
Naufahu signed for the Southland Stags in 2000 and before returning to Christchurch to play for Canterbury in 2001.
He joined English club Leicester Tigers in 2002, playing five games before moving later that year to the Glasgow Warriors.
But his knee problem restricted him to eight appearances in Glasgow before he had to hang up his boots.
Naufahu told BBC Scotland he loved his time in Glasgow and fondly remembered parties in Ashton Lane.
"I will come back one day and have a turbo shandy [a lager and Smirnoff vodka concoction] - you don't get older and wiser," he said.
"The weather made for a different style of rugby to what I was used to back home, where there's generally a faster track and opportunities with defences being freer, but I had mad respect for the boys playing and coaching in Glasgow. For me, it was just a case of not enjoying the rugby so much because of injuries.
"As rugby players, you have a pre-built community that you walk into. You don't really have to go outside it, but at the same time it's a little bit of a bubble and when it pops you're like, 'what do I do now?'"
His path ultimately led to Game of Thrones, now in its eighth and final series.
Naufahu also starred in a home grown movie - The Kick - detailing the story of Stephen Donald's match-winning penalty in the 2011 Rugby World Cup final.
He played former All Blacks fullback Mils Muliaina.