25-year-old CEO shares the career-killing mistake many young professionals make

Brian Wong, 25, is co-founder and CEO of mobile advertising company Kiip. The company works with big name brands like McDonald's and Pepsi and is on track to bring in an estimated $21 million in revenue this year.

Never one to adhere to traditional timelines, Wong finished college at 18 and has used a series of "cheats" to fast-track his career. Now, he jets back and forth between Kiip's offices on the East and West coast each month.

Wong says many young professionals make one common mistake that slows their career.

"Thinking that people won't take you seriously before you enter a conversation," Wong tells CNBC, "is one of the biggest mistakes [early-career] professionals make."

Brian Wong, chief executive officer and co-founder of mobile advertising company Kiip.
David Paul Morris | Bloomberg | Getty Images
Brian Wong, chief executive officer and co-founder of mobile advertising company Kiip.

According to the CEO, if you go into a meeting assuming that you don't have value to contribute or sit in the corner of the room and don't talk at all, you're making a crucial error.

"Confidence and poise are critical," says Wong, who discusses his career tricks in the book "The Cheat Code."

Young professionals don't have to fake their confidence, either. They are perfectly positioned to help executives tackle some of the most difficult corporate problems today, he says.

"Confidence and poise are critical." -Brian Wong, CEO and co-founder of Kiip

"The biggest challenge of any C-suite today is two-fold," Wong says. "One is to understand the new generation of customers that's emerging and the second is to retain millennial employees."

Professionals in their early twenties can help companies reach younger, digital-native consumers and retain employees similar to them.

That perspective is "very valuable," he says.

Check out 7 body-language tricks to exude confidence

Video by Andrea Kramar.