In the last financial year, the 25-year-old's digital marketing and advertising company, Insil, turned over $2 million, a far cry from Zanner's life in 2016. He says it's proof you don't need to be good at school to be successful.
"I wasn't an A-grade student, not even close, because I often spent time thinking and dreaming of life outside school, the real world," he told Yahoo Finance. "I've always had a very practical realistic approach to life, so I often clashed with teachers. Why would I want to learn calculus? No one ever uses it outside school."
While Zanner, who's from Sydney, daydreamed about the future, he completed his PT certification while still at school, with plans to open a business the moment he could. But, by the time he was 18, Zanner found himself studying business at university in Canberra and completely unfulfilled - as if he was following someone else's dream and not his own.
He calls this rock bottom.
"I just remember having no money, being bored and, most importantly, questioning why I was put on Earth and what my value to society was," he said.
So he picked himself up and moved into the fitness space where he could help others and do good. "Fitness has such a profound impact on mental health and this is something I was always passionate about."
Yet Zanner had even bigger dreams.
"Fitness was great, but I wanted to have a bigger impact with more reach," he explained. "Digital marketing lets you do that. Collectively, we influence millions of people each month with our campaigns, creating multiple seven-figure brands."
But it wasn't easy, Zanner admitted, and there was an endless list of challenges to conquer. While he was able to live back at home with his family, he kept afloat with a few side jobs and used the last few dollars from his PT business to create Insil.
"I always had an innate drive to succeed. A deep curiosity that's always encouraged me to question why things are done in certain ways but, more importantly, what a better future would look like."
Secrets to success
While Zanner said the will to be a standout entrepreneur was strong in his generation, he explained that he'd collected a few lessons along the way on how to become a self-made millionaire.
"Become customer-obsessed," the 25-year-old said, borrowing a lesson from Jeff Bezos, the founder of Amazon. "Worry about this first, money will follow."
Then, there is just getting on with it.
"Execute," Zanner advised. "Just do. This is where so many fail, they just don't put the work in."
Getting up hours before others also helps.
"Do it early. Most people only start their day from 8.00-9.00am. I'm active from 4.30am every morning. I do this to buy an extra three to four hours every day. It gives me an extra 15 hours every week, compounded over a year."
Then there's looking after your employees through incentives.
"Staff should be incentivised according to the client's goals," Zanner explained. "It's one of our biggest points of difference. Our team actually has a huge vested interest in our clients succeeding. They're almost like internal business partners."
The entrepreneur's final lesson is about living on 20 per cent or less, and giving as much as you can to the company. "Reinvest in your business," he said. "And most importantly yourself."