And now he has graduated from university - the first in his family to do so.
Speaking to the Bay of Plenty Times from his Salt Lake City apartment, Mr Melligan said he had come a long way.
"I was going to town every weekend, but I often thought, there has to be more [to life than] living weekend to weekend.
"Because that's what I was doing, working, getting my pay cheque and then going to town with my friends."
A friend invited him to a church dance when he was about 20.
"I saw that they were happy and had fun without alcohol.
"This really intrigued me, having fun without alcohol or a hangover the next day.
"So, I decided to attend church and started learning more about the gospel of Jesus Christ - this helped me to find happiness in living a wholesome life."
He started a two-year mission with the Church of Jesus Christ of Latter-day Saints to the Netherlands but cut the trip short, suffering from anxiety.
He was then re-assigned on a six-month mission in the Pacific area including Australia, New Zealand and Papua New Guinea which focused on community service, interfaith, community and government relations.
"I was surrounded by people who had degrees, people who had good life visions.
"That's when I knew I could go to university."
He came home and completed an academic bridging course at the former Bay of Plenty Polytech and applied to the LDS Business College in Salt Lake City.
In January 2016, he started a degree in Associate of Applied Science in Social Media Marketing.
Last month he graduated.
He cringes when he looks back on his past.
"It's amazing to know that I can use what I am passionate about for good and I know others can too, that's why I wanted to share my story with Tauranga.
"Even if you have been up to no good, you can turn your life around and use talents to help others, to make a living and to contribute to the goodness to the world."
Through his degree he was able to work with his peers to raise over US$300,000 ($436,434) for a school district in Utah which has a number of refugee children.
He recently headed to Anaheim, California, with friend Hunter DeVries and the pair were representing the Utah state and LDS Business College at the DECA International Career Development Conference where they will be competing in emerging technologies.
He will return home for two weeks before starting his social media internship at the Church of Jesus Christ of Latter-day Saints. He was excited to be heading home to spend time with his family.
Eventually, he wants to retire in New Zealand but after he has set up social media agency in the United States.
Mr Melligan's mother, Tina, said she was blessed and honoured to have raised such a brilliant young man.
