"This is going to be like school."

Marcus Lemonis is as direct and in-your-face offscreen as he is on the television show The Profit. After his opening line at the joint Inc. and CNBC iCONIC conference in Los Angeles on Tuesday, the reality show star and entrepreneur proceeded to march to the back of the Ace Theater to induce attendees to sit closer to the front of the room. In some cases he led them by the arm.

What followed was indeed a bit like school--and a massive group therapy session.

"The key to life is being yourself," Lemonis said. To drive the point home, he spent the next 10 minutes revealing the worst about himself to about 400 conference attendees. It was quite a far cry from what fans ofThe Profit are used to seeing. 

Here's the short version: Lemonis spent his adolescence overweight, struggling with an eating disorder, lonely, and friendless. He was molested by a family member--something he hadn't revealed to anyone until just last year. Still to this day, despite his wealth and public persona, Lemonis revealed he worries that people are going to find out he's not as smart as they think he is and that he will die alone.

"I'm wildly insecure," he said. That's surprising, considering his success. Lemonis is the CEO of Camping World, a recreational-vehicle business he started in 2002, which has grown to 132 stores, 7,000 employees, and close to $3 billion in revenue.

The purpose of his brutal honesty at a business conference for entrepreneurs?

"The truth in life is about connecting to people through vulnerability," he explained. "Life is not--and business is not--just about business. It's really about people. It's about establishing relationships that truly make a difference. I hope you feel a little more connected to me now." 

At Lemonis's prompting, members of the audience shared their own difficult stories and vulnerabilities--stealing as a child, experiencing racial discrimination, dealing with an unplanned pregnancy, struggling to manage employees who underperform.

He was every bit the tough-love coach he is on camera, when he walks into failing small businesses around the country and tells entrepreneurs the tough things they need to do to turn them around. He fired off questions like: "Who set the bar for you? So it's self-inflicted? Are you reasonable in those expectations? Why is this so hard for you to talk about?"

But in the end Lemonis's message was simple: "I want you to have a purpose."

To that end, he left the audience with one final rule to live by: "I make every decision in my life with a particular face in mind. Even the deals I do in a flash. ... I think about what my mother would say."

What your mother thinks of you matters, Lemonis said. "But what you think of you has to matter the most."