By age 30, Grant Sabatier had earned over $1 million through a combination of reducing his spending and boosting his income.

He believes that lots of people could earn extra cash in much the same way he did: In addition to negotiating his salary at his marketing job, which started at $50,000 a year, Sabatier worked up to 13 side hustles at a time to bring in more income, doing everything from flipping domain names to buying and selling Volkswagen campers.

But if you want to significantly boost your earnings, he says, you first need to get past the myth that time is money.

"It's everywhere in our world and our culture," he tells CNBC Make It. "I remember my parents telling me it when I was a kid. But in reality, time is not money at all."

Money is limitless, while time isn't: "You can always go out and make more money," he says. "You're never going to get back your time. Once this moment is gone, you're not going to get it back forever."

Most people picture a direct correlation between time spent and money earned, he says, assuming that, if you work X hours, you earn Y dollars. But although you can't change the number of hours you have, you can increase how much you earn in that time.

Sabatier's secret? Trade other people's time for money. "The simple idea here is that you want your money to be making money and other people to be making money for you," he says.

Take dog walking, for example. If you walk each dog yourself, you're limited by the number of hours you have. But if you connect other people with dog owners and take a cut of the profits, you're able to hire as many dog walkers per hour as you can find, Sabatier explains.

"All of a sudden, you're no longer limited by your own time to make money," he says. "You're trading other people's time and compensating them for their time. So you become a connector between supply and demand."