Self-made millionaire and serial entrepreneur Scott Galloway says there are two critical secrets to success: Following your passion is "bulls---," and pick a good life partner.

Passions might not bring you financial success

"[Return on investment] and sex appeal are inversely correlated. What do we mean about that? Simply put: Don't follow your passion," Galloway, who sold his company L2, Inc., reportedly for over $130 million, tells CNBC Make It. Instead, focus on your talent. "Find out what you're good at and then invest 10,000 hours in it — and become great at it," Galloway says. Telling people to "follow their passion" is popular advice, but Galloway, who is also a marketing professor at New York University Stern School of Business, doesn't buy it. "People often come to NYU and say, 'Follow your passion' — which is total bulls---, especially because the individual telling you to follow your passion usually became magnificently wealthy selling software as a service for the scheduling of health care maintenance workers. And I refuse to believe that that was his or her passion," he says.

NYU professor Scott Galloway Tobias Hase | Getty Images

Successful people are generally enamored by the trappings of their success, Galloway says, and they can conflate the trappings of wealth and power with a passion for what made them successful. "What they were passionate about was being great at something, and then the accoutrements of being great at something — the recognition from colleagues, the money, the status will make you passionate about whatever it is," Galloway says. Common places for people to feel truly passionate — like sports, films and restaurants, says Galloway — require a lot of time and don't generally don't lead to financial success. "So if you want to go to work for Vogue or you want to open nightclubs or you want to produce films," you need to be prepared for a modest payout for your labor, Galloway says. Galloway isn't the only successful entrepreneur who warns against following your passion for financial success. Billionaire tech entrepreneur Mark Cuban, currently worth about $4 billion according to Forbes, wanted to be a sports star but realized he was never going to make the big leagues. "One of the great lies of life is 'follow your passions,'" Cuban said on the Amazon Insights for Entrepreneurs series. "Everybody tells you, 'Follow your passion, follow your passion.'" Like Galloway, Cuban also recommends doing what you're good at. "When you look at where you put in your time, where you put in your effort, that tends to be the things that you are good at. And if you put in enough time, you tend to get really good at it," explains Cuban.

Choose the right life partner

The second key attribute to success, according to Galloway, is picking a good life partner. "The most important decision you will make for happiness over the course of your life is who you decide to partner with — not professionally, but personally: your mate, your spouse," says Galloway. And important criteria for picking a partner is find someone with whom you're aligned on values and big-picture questions. "What is your role in the household? Where you going to live? ... What is your viewpoint on the number of children you're going to have...? These values based conversations are key because they can be incredible potholes if you don't align on them," Galloway says. You also have to agree on how to earn and spend money, he says: "Who is going to make the money? ... Is it both of you? How much money do you expect to make and how much money do you expect to spend? ... What will your lifestyle be?"