"Round about 14 is a good age to start. Their levels of concentration are better and they know that they want to do boxing rather than dad pushing them to do to it," he says.
Grant says boxing also has benefits outside the ring for overweight kids, bullies and victims of bullies.
"We get kids who are not doing so well at school. They take up boxing and their level of education rises, their confidence rises. We've had feedback from schools about kids who have been turning into decent kids through boxing training."
Boxers starting out need track pants or shorts, gym shoes, hand wraps and a mouthguard. The gym provides gloves, headgear, mouthguards, and punching bags. As they progress, some kids may invest in groin guards for boys, girls have breast guards.
It takes at least six months to be competition-ready. At that stage they need a medical book and an annual medical check-up. Fights are watched closely and rules govern what areas can be hit.
"In the amateur fights, the refs are very strict, if a kid gets on top of another they slow it down or stop the fight."
Chas Tugaga-Maxwell trains with Grant. "I thought it would be a good change from netball and athletics.
The 17-year-old's Dad taught her some boxing basics. "He gave me that motivation.
"I like having a general knowledge of boxing and knowing I can use it for self-defence. And it helps me with my mental toughness."
Nikki Adams started boxing at 19 and has won national titles.
"I started off just for the fitness but watched a few fights at the gym and thought 'that could so be me'."
She trains under Cameron Todd at City Boxing.
"I was always the type to involve myself in sport, do well, then quit because I didn't like the commitment. With boxing it was different, so it's what I'm focusing on doing with every other aspect of life. When things get hard, don't give up."
But what about those concerned it is a violent sport?
"I had that issue with my parents," says Nikki, "especially since I'm a girl and they didn't want to see me get hurt. But there's always going to be injuries no matter what sport.
"My parents saw I loved it and now support me. "
Chris Lynch, sport and exercise science lecturer at Unitec, says participation in any sport for young people is beneficial. "Whatever sport you choose, knowledgeable instructors who understand children and young people's development is important. Boxing has real potential for injury and that should be a major consideration but in a reputable environment if a young person picks that as their sport it is as beneficial as any sport to participate in."
To find a gym near you, visit boxing.org.nz or ph 04 389 0890.
