Getting your product in the hands of customers can take years of nonstop hustle. Take it from KIND Snacks CEO Daniel Lubetzky, who says a relentless work ethic helped his company double its annual sales for more than 10 years in a row.

In a video interview with Inc. editor James Ledbetter, Lubetzky says when he was first starting out he traveled all across the country to visit buyers at supermarkets. He would wake up at 5 a.m., and sometimes wouldn't finish selling until 11 at night.

"We went door by door to every single Whole Foods store," he says. "I talked to every buyer at every one of these stores. I crisscrossed the nation. If you tell me where you're from I probably can tell you where your favorite supermarket is."

It wasn't until about six years after KIND Snacks was founded that word of mouth really began to spread. By 2012 the company had $125 million in sales. But even then, Lubetzky was still making a great effort to introduce people to his product.

"It is so hard when I'm on a plane and I'm exhausted and I'm afraid of rejection to stand up and offer to a stranger a KIND bar" he says. "It's not easy but I rise to try to do it."

A decade and a half after founding KIND, Lubetzky says he still fiddles with product displays in grocery stores and carries boxes around at trade shows because he believes the minute you stop hustling is the minute you lose your edge. 

"I'm terrified that if I ever stop giving it everything I've got and I stop grinding, that I would look back five years later and that would be the moment when mediocrity started seeping into who I am and who my organization is," he says.