Bruno Mars has built his career on infectious pop melodies and perfecting one key skill: honesty.

The Grammy-winning artist, 37, tells CNBC Make It that learning to trust his gut and cultivating extreme self-discipline has helped him succeed in music and business.

“Whatever you’re doing just has to be honest — that’s really become the most important thing for me in my career,” Mars explains.

“So if I’m writing a song, I have to be sure that this is the best I can do, deep down in my soul, and that I didn’t take any shortcuts. I have to really believe in what I’m doing for it to work.”

Mars got his start in music as the world’s youngest Elvis impersonator in Hawaii when he was just 2 years old, moving to Los Angeles after graduating high school in 2003 to pursue his dream of becoming a singer.

“There’s something beautiful about being young, naive and uneducated … you’re just free to fly,” Mars says.

He quickly became one of the most sought-after songwriters in pop and R&B, collaborating with the likes of Adele, Alicia Keys and Jay-Z.

Where his gut instinct really shines, he says, is making smart investment decisions. While Mars has made few endorsement deals over the course of his career, he has invested in a select number of companies, including NJOY, a private e-cigarette company, and Chromatik, which creates digital versions of sheet music.

In March 2023, Altria Group, which sells Marlboro cigarettes in the U.S., bought NJOY for about $2.75 billion.

Chromatik, meanwhile, was acquired by TakeLessons, an edtech company, in 2017 for an undisclosed amount after raising over $7 million in funding.

According to Mars, tapping into your intuition “doesn’t get any easier” with age and experience. In fact, he says, “it’s gotten harder” for him.

Being clear about his career goals, Mars adds, has helped him to only commit to projects that he is excited to work on so that he doesn’t burn out. In 2014, Mars became a co-owner of SelvaRey Rum, a Los-Angeles based spirit label that was launched that same year by brothers Seth Gold and Marc Gold and their brother-in-law, Robert Herzig.

In a statement to CNBC Make It, SelvaRey said it’s one of the fastest-growing rum brands in the U.S., however, as a private company, they declined to share specific revenue or sales figures.

As Mars has learned, success feels “a lot better” when it’s something you genuinely want, and worked hard for.

“You have to be able to sleep at night,” says Mars. “If the world didn’t respond to a song I wrote, I can still sleep at night knowing that was the best I could do.”