Kiwi boxer David Tua is a man whose determination is shaded by one shining light - his Christian faith.

Speaking ahead of Saturday's bout with Monte Barrett, the dry-witted Tua said the fact he was still boxing today was proof he was able to conquer the previously circling cynicism that was as big as Goliath.

"I don't think my future depends on the outcome of this fight.

"I've been counted out many times. I think for me I've always fought above my weight. My name is David, the division of giants, and I've been very fortunate enough to do some decent things in the sport.

"I'm still living and I'm still doing it, so you know to do it this long is a miracle in every way."

Tua, whose Christian faith often has people questioning why he is involved in what is a brutal way to make a living, says he has 'his ministry' to thank for helping him save his life.

"[Boxing] has put in perspective what mum and dad have taught me as a young fulla. But still, I wasn't around Mum and Dad 24 hours a day.

"I know when I was in the gym I wasn't on the streets. If I wasn't on the streets I wasn't in jail. That's how I look at boxing and what boxing's done with me.

"So boxing is my ministry. It connects me with the people, it connects me with the young people.

"As a Christian people say this and that but for me if I can make a difference in one kid's life, and that rolls over to the next and they help another kid, then as far as I'm concerned then the glory returns to the Father because what I do is not who I am."

Coming up against a fellow Christian in the form of the 40-year-old Barrett, the humble Kiwi boxer said he has prepared for it well and his focus is the only thing left to pinpoint after another media session.

"I'm pretty upbeat and pretty positive about this fight. I'm well prepared for it and I've just gotta stay focused little bit more. I've got a couple more days to stay on top of things."

Before leaving, Tua discusses his favourite excerpt from the Bible - Psalm 139 - that tells of King David's, fitting, love for a God who knew all before it had been made.

"All day, the whole thing. I knew you before you were born, man, I knew you before your parents met.

"That's how I look at my life and what I've been fortunate to do. At the end of the day it's all about the heart."

And to kids for whom his 'ministry' speaks to, the inspiration they surely receive from Tua reaches to the most important part, the heart.