'Shark Tank' judges Kevin O'Leary and Robert Herjavec got into a fight about when you should quit your job

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Last Sunday's "Shark Tank" had its share of tense moments, but the toughest came when judges debated a thorny question many entrepreneurs face: Can you be truly committed to your startup if you haven't yet quit your job?

The sharks' debate raises some important points for any entrepreneur balancing passions and responsibilities.

Contestant Keisha Smith-Jeremie came to the sharks with Sanaia, an applesauce targeted to adults. The venture had already raised doubts with the sharks thanks to its hard-to-ship glass jars and her confusion over product interest and actual product sales.

But Smith-Jeremie also held down a full-time job as a head of human resources at News Corporation. This was a dealbreaker for some of the sharks, sparking a heated back-and-forth.

"If you really believed in this, you'd quit your job," said shark Kevin O'Leary.

That wasn't possible, Smith-Jeremie explained. She was her family's breadwinner. Quitting "isn't an option for everyone," she added.

O'Leary was unmoved, explaining that he could simply invest in entrepreneurs who had quit their full-time jobs.

Robert Herjavec backed her up, saying O'Leary wasn't being fair to this founder. But shark Mark Cuban weighed in further questioning Smith-Jeremie's commitment. "I get you're a breadwinner. That's always a push-pull that people have," Cuban said. "But at the same time, we all were broke. I'm not convinced."

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Smith-Jeremie argued back, explaining she'd self-funded her business and invested her life savings into it. For her, she said, Sanaia was not a part-time job.

The answer did not satisfy O'Leary. "Why aren't you throwing everything into this?" he asked.

This question took Smith-Jeremie to her breaking point. She began to tear up. "I can't afford it," she said.

Robert Herjavec stepped in, saying he understood the pressures Smith-Jeremie felt. He'd felt them too. "I started my first company, I wanted to be all in," he says. "You know what? I had a mortgage, I had a child at home, I didn't have that choice."

"Kumbaya!" O'Leary shot back, interrupting him. He felt that the world was not fair and she needed to be able to compete in that world.

"She's not asking for a 'kumbaya,'" Herjavec responded. "She's just saying she has a family to support."

Attentions eventually turned back to Smith-Jeremie and why she'd teared up. She explained she not only supported herself financially, but her parents and siblings, too. "I'm the person who made it," Smith-Jeremie said to the now-silent sharks.

The powerful moment marked an important turning point. "You're absolutely right to keep your job and take care of the people you're taking care of, and fulfill your dream on the side," said shark Lori Greiner.

Cuban, who'd raised many doubts about the company, was finally moved to invest. He struck a deal with the founder, offering her $150,000 in exchange for a 25 percent stake in the company.

Once she left the tank, he explained how her story helped him better understand what drove her. She'd come in cool and professional but not passionate. It wasn't until she became emotional that "the entrepreneur in her came out."

"I wanted to know if it mattered to her," Cuban explained. "I wanted to know if she was all in."

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Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."

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