Jeffrey Morgan spent 18 years in prison for bank robberies, after growing up at Redfern's Block in the 1980s.
Before long stints in maximum security prisons, he spent three years in Mount Penang Juvenile Justice Centre on the Central Coast from age 16 to 18.
He returned there on Thursday for the first time in more than 30 years, speaking to senior staff about leadership, mental health and suicide prevention.
The site, now known as Frank Baxter Youth Justice Centre, is more like a proper prison nowadays.
"Mount Penang was like an army barrack, where you could run off into the bush if you wanted," he said.
His return felt like "a way of giving back and being grateful".
Mr Morgan, now 50, has turned his life around through education and self-development.
He completed a Bachelor of Nutrition through Deakin University and subsequent courses on mental health, wellbeing and emotional intelligence.
He now runs a business giving self-help talks, including to NRL teams through the league's wellbeing program.
"I tell them what they need to hear, not what they want to hear," he said.
He's come a long way from living on the streets of Sydney at age 12, after escaping a chaotic home.
He had lived in Eveleigh Street in Redfern, one of the most notorious streets in Australian history.
"Riots with police, domestic violence, drugs and alcohol were normal. Police wouldnt go down there," he said.
He met other homeless kids and graffiti artists.
"I became destructive and dysfunctional. It was a normal way of survival in our eyes," he said.
His life changed when four private school boys from Waterloo, near Redfern, were sent to Mount Penang for murder.
"I knew them. They grew up in the area in good homes," he said.
He was with them on the day of the murder, but in a twist of fate was offered dinner elsewhere and wasn't involved in the crime.
But after snatching money off bank counters and being charged with "robbery in company", he too ended up in Mount Penang.
While there, he looked after the Waterloo boys and they urged him to join a school program on offer.
"There was only five of us in class," he said.
He recalled the teacher was named Miss March.
"She instilled different habits and rituals in me. She inspired me, saying 'you can do more, Jeff'.
"They were little bits and pieces that my father and mother never gave me."
But old habits die hard, so it took years to change his entrenched behaviour and find redemption.
He committed armed bank robberies in Sydney and Melbourne and was jailed for five years and then seven more.
"I was trying to survive. Honestly, I didn't think I was doing anything wrong," he said.
"I had to make money and needed somewhere to sleep and get food.
"I became what I was around. It doesn't excuse it. But I recognised it and wanted to be better."
He worked on changing himself.
"I went from destructive to constructive. There are behaviours we can shift when we change our perspective."
As a young Indigenous man, he said it was "a badge of honour to go to jail and say you were from Redfern".
"People feared us," he said.
"I'm not proud of that person, I'm proud of who I became."
