When he was 17, he went through what he describes as a "major depressive episode".
"As time went on, it got worse, I turned to alcohol and self-harm," he said. "I just stopped taking care of myself."
When he reached 18, Nathan was admitted to a private psychiatric hospital.
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READ NOW"It was my lowest point but I always had hope I would get better and I held on to that," he said.
He was in an out of hospital for six months, trialling 30 to 40 different medications before he was diagnosed with bipolar disorder.
"It took four admissions over six months before I was diagnosed," he said.
But Nathan said it was not until he had a reaction to a new medication that he really took his health seriously.
"I was home alone and my muscles started convulsing; it started in my jaw and began constricting my airways," he said.
"I had to text a friend because I couldn't speak. I told them to call an ambulance.
"By the time the ambulance came, I was turning blue, and was in and out of consciousness."
He said after that, he really put the effort in to getting better.
"The more effort I put in, the better I felt," he said.
He described getting better as a full-time job but said he could now identify triggers and emotions before things got out of control.
"That hope I held on to still helps me," he said.
Nathan will share his story at a youth mental health forum held by Ascot Rotary this month.
The forum will also feature speakers from mental health support services.
If you or someone you know may need help, contact Lifeline on 13 11 14. Youth mental health forum When: May 21 Time: Doors open at 5.30pm- live music, forum starts at 7pm Where: Forster Park community centre, Cnr Keane Street and Abernethy Road, Cloverdale Light food provided