"It's toxic, and full of chemicals. I went from using a packet a week to a packet-and-a-half a day in three months - it's that addictive.
"At $20 a packet I also went through heaps of money. Some of the effects are far worse than taking hard drugs, it blows your mind."
Heginbotham confessed to taking hard drugs in the past, including methamphetamine.
He said he got himself clean and had stayed clean after admitting himself to Salvation Army Bridge Programme about a year-and-a-half ago.
He turned to synthetic cannabis because it was legal and he could buy it in dairies.
Last year he was made redundant. He was not working at the time of the robbery, had become depressed and started using synthetic cannabis to help him relax.
Heginbotham said on the day of the robbery he was planning to pick up his girlfriend in Mount Maunganui, but never made it and an hour later he was robbing the dairy while in the midst of a major withdrawal.
Heginbotham said it was like he was acting in some kind of "brain fogged" state.
"When I talked to police I couldn't even tell them how I even came up with this hair-brained scheme. I thought, 'Oh my God, what have I done?'. I was freaking out and couldn't even process it.
"This just isn't me, it was another person I didn't even know. I would never want to hurt anyone, I'm just not a violent person, and never imagined myself doing anything like this."
A tearful Heginbotham said synthetic cannabis had ruined his life.
"I'm not asking anyone to feel sorry for me. Yes, I did this horrible thing but I never intended to hurt anyone. I have not only hurt myself, my mum and dad, my friends, my neighbours, the people I robbed, and probably the whole neighbourhood. The old lady next door won't even look at me."
Heginbotham said he had completely stopped taking legal highs since his arrest, and had also stopped smoking cigarettes. He wanted to help other people kick the habit too.
"I would love to help kids, especially those whose parents probably don't even know they are on this s***, and are also ruining and wasting their lives.
"By speaking out I'm trying to do something positive from this and if I can help even one other person to understand how addictive this stuff is and stop wasting their life, I'll feel happier.
"If it did this to me in three months it could easily strip the life from a teenager in a month," he said.
Heginbotham's mother Susie said her son had an "addictive personality" and has had many struggles with drugs in the past but has never been in trouble with the law before.
Hanmer Clinic senior clinician Jill Knowler said cannabis smokers were turning to synthetic cannabis as natural cannabis was becoming harder to come by.
"But it's nothing like cannabis. I see people presenting more like something close to people high on methamphetamine. The best thing is to help them get off it, clients are telling us it's very addictive. What I'm seeing on TV about what it does to people, that's what we're seeing. It's not exaggerated."
