"When I came here and got to know Craig better, I found out that there's more to life than just trying to be mischief - that you can find fun doing other things, positive things. You don't have to be drunk to have fun in the weekends."
The academy, where Mr McDougall is head coach, changed his attitudes.
"When I first started here it was for all the wrong reasons - I wanted to be a tough guy pretty much," Mr Hepi says.
"There's a real family feel here, which is what I like about it. It's helped me a lot, not just in the ring, but outside - they give you good advice, they look after you and they back their word up, too, when they say they'll do something."
Mr Hepi was one of four boxing academy members to fight competitively for the first time this year. He won in Lower Hutt on points: "I was over the moon when I won. I felt like jumping up and down - a good feeling."
Success at the academy had also brought his family closer together.
"Me and my dad and my mum would never really do stuff like this. Now my parents have seen how much it's changed my attitude and my life and they're really excited about this. They're excited about the club and they're excited for me. They see how positive Craig is."
Mr McDougall said he was "blown away" when Mr Hepi opened up to him for the first time about the positive impact the academy was having on his attitude and relationships.
"I just thought, 'wow!' That's one of those moments that reminds you why we do this stuff. It was awesome, a really powerful story at the time," Mr McDougall says.
"Now Willy is a mentor to our young fellas. He'll hug our young boys when they come in so they understand that big, strong men are okay with loving people - it's perfectly normal and it's what's supposed to happen."