The U.S. business concept of customer service has long been typified by the mantra, "The customer is king."

But not for Marcus Lemonis.

The entrepreneur and host of "The Profit" is blunt about whom he thinks you should rank ahead of the customer if you want your business to succeed.

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"The customer is not Number 1," Lemonis said. "They're Number. 2, right behind the employee."

Lemonis provided three keys to building a better business by building better relationships with employees.

"If the employee is happy, then the chances of the customer being happy are exponentially better," Lemonis said.

He pointed out that employees are the people on the front lines, ringing the registers and greeting the customers that keep your business running smoothly. Treat them right and your business will thrive.

"If you want to be successful in business, you have to get down on the level with everybody else," Lemonis said.

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An owner will not understand a business completely unless they get their hands "dirty" working from the very bottom rung of the business to the very top.

"I truly feel like I can go into almost any business, doesn't matter what it is, and have at least a decent chance of fixing it because I use three simple principles: people, process and product," Lemonis said.

You have to challenge the product if you want to be successful—ask if it is as relevant as it can possibly be and if you have the most efficient system in place for that product.

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But the "P" in people is the most important of the "3 Ps" that serve Lemonis' primer on how to get a business headed in the right direction.

"If I like the people and I believe in what they believe, I sense their passion, their work ethic, their integrity, their character. … I'll take a chance on anybody and anything," he said.