But the heavily tattooed 34-year-old, who cheerfully admits to a "colourful past", including 20 years in a gang, drug and alcohol addictions and periods in jail, has his eyes on a PhD.
"My tutor said to me: 'Imagine that, doing a PhD'. I said, 'Well, who knows'. I have big dreams ... I have developed a passion ... to carry on with my study. I want to get to the peak of what I can do. My addictive personality can go into something positive."
Of Ngati Porou descent, Mr Addison was raised on the East Cape north of Gisborne.
Three years ago, with wife Audrey and their two young sons, Tama (now 5) and Jamie (now 3), he moved to Dunedin to escape the gang lifestyle.
His first goal was to complete an addiction programme at the Dunedin residential facility Moana House; the second was to gain a qualification; the third was to find a job.
Now, he has achieved all three.
Mr Addison will today receive a national certificate in mental health and has part-time work as a kaiwhina - a peer support staff member - at Moana House.
Next year, he intends to study for a diploma in applied addictions qualification through Moana House while continuing to work part-time.
His aim is to become an addiction counsellor.
"It is my way of giving back ... If it wasn't for Moana House I would probably be somewhere undesirable. Moana House saved my life".
Mr Addison said he had not been sure how he would be received at Otago Polytechnic, or even if he would be accepted.
He left school at 13 unable to read and write, finally mastering the skill "receiving and writing letters and reading [women's magazines]" in prison.
But he said he had always felt accepted at the polytechnic and appreciated staff and students giving him a chance and "looking beyond the tattoos on my face to what's inside".
He was also pleased to find, although his full-time study this year was "challenging", he was able to cope with the mix of classroom work, assignments, online research, community placements and "lots and lots of reading". Mr Addison agreed to be interviewed because he did not want young people to waste their lives.
"I say this with a bit of emotion ... Don't wait till you're 34 and figure out you could have been so much more.
"And love your mum."
