Billy Graham -- national title-winning boxer and 2011 New Zealand Local Hero of the Year -- pulled no punches during his guest appearance at Rathkeale College on Wednesday.
School spokesman Grant Harper said the past New Zealand welter-weight boxing champ had, during his time on stage, sent rounds of laughter circling through an audience that included students from the boys' school and senior girls from St Matthew's Collegiate School.
"His highly animated and humorous address drew on a wealth of lifetime experiences and was full of helpful advice for his young audience," Mr Harper said.
Graham has dedicated the past decade to working with underprivileged and troubled youth and in 2006 he and his wife Kerri sold their home to found the Naenae Boxing Academy, which bans drugs, gangs, bullying and swearing, and aims to turn young boys into "champion men".
After a specialist consultant worked alongside Graham to evaluate the successful Naenae model, the champ in 2014 opened the Cannons Creek Boxing Academy, which operates under the same philosophy.
Naenae Boxing Academy trains up to 100 boys and young men aged nine to 24 at a time, and there is always a waiting list to join. Graham promotes goal-setting and determination and the values of honour, decency, loyalty and respect among the boys who train under him.
Police say the gym had helped to cut teenage crime rates and tagging in Naenae. The gym had also produced champions including Youth Commonwealth fighter Keegan O'Kane-Jones.
There were hopes the model could be rolled out to communities in need throughout New Zealand.