He worked four blue-collar jobs in his teens to stay afloat. Today, his fintech startup is worth $8 billion

The word “burnout” isn’t in the dictionary of Jack Zhang, co-founder and CEO of fintech company Airwallex.

“I never understand that terminology to be honest. I’ve worked 100 hours a week from [the] age of 16 for 20 plus years,” Zhang told CNBC Make It.

For Zhang, hard work meant survival. At age 15, he moved away from his hometown of Qingdao, China to Melbourne, Australia alone, to pursue better opportunities. He barely spoke English and stayed with an Australian host family.

Shortly after arriving, he learned that his parents had found themselves in financial hot water back in China, and that he would have to support himself through university.

“I [had] two choices: either I just return to China and try to go back to the education system there, or I continue to stay in Australia and figure out how to pay [for my] tuition and living [expenses] on my own,” said Zhang. He decided to stick with the latter and took whatever work he could find to make ends meet.