As a serial entrepreneur, Mr Brad Robinson had his fair share of business partners over the years. After all, he has set up five companies in the securities and lifestyle industries, three of which he is a silent partner in.

But none of them was quite like Mr Ian Tan, says the 37-year-old.

"People find business partners while trying to chase opportunities or financial gain. But in our case, I have competed in professional fighting events and had this guy in my corner, giving me advice the entire time.

"If you trust someone enough to go into combat with him, then the business stuff is easy."

Still, even though they were fast friends with a solid business plan when they decided to start Ritual, Mr Robinson knew it was important to set ground rules off the bat. The most important of the lot? "Real talk," he says.

In fact, one of the first agreements the two made - before they started Ritual - was to be brutally honest with each other. "I told him then - if I p*** you off or overstep my boundaries, don't keep it in for the sake of keeping the peace. Just tell me," says Mr Robinson.

That fighting spirit - in the ring and outside - is what has kept their relationship strong.

Both also agreed early on that if something was not working, they would tear it down and rebuild it. This fearlessness to take risks and admit mistakes has led to much of their success, such as their decision to rejig their app over the past year and invest money to make it better.

"You have to be willing to change things that are wrong. Working with Ian has taught me the importance of always gunning for quality," Mr Robinson says. "He's always ready to find out what went awry and fix it - it's a continuous quest to be better. What could be more inspiring than that?"

They try to hang out outside of the office as well, mostly hunting down good food. "We work in the fitness industry, but we love our food," Mr Robinson says.