If you're a Gen Z professional hoping to hear inspiring advice about following your dreams, Robert Herjavec has some uncomfortable news. The Shark Tank investor is channeling some brutally honest career guidance that might sting a little.

The Obsession Distinction

During a Shark Tank taping, fellow billionaire Mark Cuban delivered a reality check that stuck with Herjavec. According to Herjavec's account to Fortune, Cuban told him: "Life doesn't care about your passion, and I don't care about your passion. What I want to know is, what are you obsessed with?"

Herjavec explained the critical difference to Fortune: "Passion is easy, because passion is a wish, but obsession is an action." Passion doesn't require you to do anything. Obsession demands everything you've got.

That philosophy resonates across Silicon Valley. Investor Naval Ravikant puts it simply in The Almanack of Naval Ravikant: "If you're not 100% into it, somebody else who is 100% into it will outperform you."

Tesla (TSLA) CEO Elon Musk exemplifies this intensity. He actually had to delete the strategy game Polytopia from his devices because his obsession with it was "taking up too many brain cycles."

Not everyone agrees with this extreme approach, though. Entrepreneur Scott Galloway offers a reality check of his own: "Anyone who tells you to follow your passion is already rich."

Playing the Long Game

Herjavec's own career path wasn't a straight line. The Croatian-Canadian businessman considered becoming an FBI detective and working in film before finding his calling in cybersecurity. His point? Obsession doesn't happen overnight, and your first job doesn't have to be "the one."

"When you're 21 or 22, you feel a desperation about tomorrow, and some of that's good because it's rocket fuel," Herjavec told Fortune. "But too many people in their twenties make snap decisions without considering the big picture."