"I think for any Maori or Polynesian music it's a good tool, because it's something they can relate to ... these kids had been through the system and no one had any luck with them but when I found that common ground, they opened up; that is how music has played a huge role in my life."
Johnson landed a record deal and started releasing tracks, which are gaining traction throughout the globe.
Despite new found fame he remained true to his passion for therapy through music and continues that work in schools.
"Most artists tour and only perform at night, but I run these workshops wherever I can during the day and then put on an evening show - I have been touring like that since July."
He shows no sign of slowing down as he tours, records and writes - both for himself and other artists such as Sons of Zion.
"I am in the middle of the next album at the moment, I had a week off touring so I went into the studio and smashed it with the producer, who came over from Hawaii.
"At the moment we are in the middle of production via email - he will send it through and I tell him what to change."
While his heartfelt lyrics remain, the reggae pop style sound is changing as he draws on other influences.
"It's a mixture of island reggae, soul and jazz, it's a fusion of many different genres."
He will be touring with BrownHill, nine Samoan friends born and raised in Wellington.
Lead singer Caesar Masoe's deep and arresting vocals struck a chord with record producer and Dawn Raid Entertainment founder, Brotha D, who recognised a classic reggae vibe, mixed with talent and creativity.
It's no secret that Pacific reggae has made huge strides on the world music stage and the boys from BrownHill are instrumental in pushing the boundaries.
"I've been following Caesar for over seven years, from his time as a solo artist, through to the growth and development of the BrownHill band," Brotha D says. "BrownHill have a cool and crisp sound."
Their debut album First Love was recorded last summer between touring duties, supporting and backing international stars such as J-Boog, Fiji and SpawnBreezie.
Catch Sammy J and BrownHill at The Sideline Bar in Napier on Saturday. Pre-sale tickets available at the venue or on the door for $25.