Australian Paul Nicholas was working as a personal trainer in New York when he struck upon the simple solution to a big problem that would change his life.

Nicholas, a former mechanic, amateur boxer and rugby player from Macksville in NSW, had moved to the US in 2001 after a shoulder injury ended his sporting career.

Working as a personal trainer in Manhattan, Nicholas was looking for a safer stability training option for both his clients' workouts and his own rehabilitation when he noticed a glaring gap in the market.

"I knew that stability training was the holy grail for rehabilitating joint injuries and strengthening your core muscles, but the only equipment available for this type of training all have you elevated off the floor making it somewhat dangerous for a beginner, and there's limited exercises you can perform with them," he said.

"One morning after thinking about it for a few months, I woke up and decided to spend the day solving this problem; I treated it like a customer had brought me a car with a problem I had to solve by 5pm, and by lunchtime I had a solution in mind.

"I wasn't looking to invent something or start a company, I just saw a gap in the market and thought I could fill it. I did some research into patents for similar devices and quickly realised that I had made something unique and new."

Nicholas poured his savings into a patent application, and in 2015, Core Flyte was born.

In a nutshell, the groundbreaking fitness device is a small triangular platform with ball bearings that roll freely in any direction, which can be used on either the hands or feet during any floor exercise.

According to Nicholas, they're so effective because they give you "more bang for your buck" during a workout by destabilising your base of support — meaning you need to really use your core muscles to stay balanced.

In the three short years since launching Flyte Fitness with co-founder Jeremy Greenberg, the company has turned over more than A$4 million ($4.3m) in sales, and it is now used in over 30 countries around the world.

Core Flyte has also been embraced by many high profile sportspeople, including Aussie surfing champion Sally Fitzgibbons, Penrith Panthers players and a number of NFL Superbowl winners.

Nicholas said the key to the company's success had been perseverance, with "a lot of sleepless nights, self-doubt, and many setbacks involved" with starting a business from scratch and putting a new product on the market.

But he also said he knew he was onto a winner fro the very beginning.

"I actually believed it was going to be a hit from day one, I don't think it would've gone anywhere unless I believed in the idea wholeheartedly from the beginning," he said.

"I think everyone has great ideas, but executing those great ideas into a product or a company takes everything you have, including your savings."

But despite Nicholas' massive success, he's not resting on his laurels.

"I'm extremely proud of what I've accomplished with this company so far, but I haven't cracked a bottle of champagne and celebrated anything yet," he said.

"We want to grow this company into a fitness brand, not just a single product."

Nicholas said he planned to expand distribution worldwide, and continue to grow the company's education workshops and courses for gyms, coaches, and personal trainers.

Several new product lines, including resistance bands, push-up handles, skipping ropes and workout DVDs, have also just been released.

He said the best part about starting the business had been the opportunity to "make a positive difference" in his customers' lives by teaching them "a better way to do things".