Beware the dangers of loving your job.

When you're passionate about something, you might want to dedicate all your time to it. You could take on more work than you can handle without realizing it, or avoid taking time off, which can lead to crippling burnout, according to Jon M. Jachimowicz, a leadership and organizational behavior professor at Harvard Business School.

While researching the topic, Jachimowicz interviewed 200 high achievers from athletes and artists to Fortune 500 CEOS. They all had the same experience: Their aspirations had, at one time or another, become more of a chore, fueling their self-doubt and stress, Jachimowicz recently told LinkedIn's "The Anxious Achiever" podcast.

"Now they're in this new phase of their life, where they think about their passion as something that they have to maintain and look after and manage very carefully," he said.

Jachimowicz's research is personal, too. He uprooted his life, moving from the United Kingdom to New York, to study worldwide economic inequality and dedicate all his time to researching at Columbia University. Within a year, the passion was overtaken by cynicism and low self-efficacy, and he felt rudderless and adrift, he said.

"No vacation is going to fix that," Jachimowicz said. "That's for sure."

Twenty percent of Americans say that they're truly passionate about their jobs, according to a 2023 Zippia report. If you fall into that category, and want to stay there, it's important to set clear boundaries and to recognize signs of burnout early on, Jachimowicz advised. 

"People feel like it's more permissible, more legitimate to assign additional unpaid tasks to more passionate employees," he said. "They're more likely to see it as an opportunity to grow and learn, or as an act of service ... because they are so passionate about this job."

How to maintain your passions — and your job

Going above and beyond at work every once in a while can be useful. Doing it too much could risk your physical and mental health, so speak up when you feel overwhelmed, said Jachimowicz.

At some point, you might start to question the work you're doing, notice that you're less productive or feel emotionally exhausted. You may need to go on a vacation, lessen your workload or do some self-evaluating to determine whether this is the career for you. This helps you avoid "passion whiplash," where you alternate between emotionally high days and emotionally low days at work, said Jachimowicz.

The fluctuation can be psychologically exhausting. "That's not good for performance," he said.

Passions change over time, Jachimowicz added. His advice: Find a job that enables you to use your strengths often and avoid toxic day-to-day situations.

"I love cooking," he said. "I'm not going to be a chef. I've watched enough of the TV show, 'The Bear,' to know that kitchens and I do not align on how we like to work."

Jachimowicz's comments echo a suggestion from billionaire entrepreneur and investor Mark Cuban, who's preached the value of following your passions in your free time — while making a career out of what you're provably good at.

"I used to be passionate about being a professional basketball player. Then I realized I had a 7-inch vertical," Cuban said in a 2018 video for Amazon's Insights for Entrepreneurs series.

Instead, he funneled his efforts into what he knew he was good at: sales and entrepreneurship. Cuban built and sold software startup MicroSolutions to CompuServe for $6 million in 1990, making him a millionaire. Yahoo acquired Cuban's second company, audio streaming service Broadcast.com, for $5.7 billion in 1999 — making him a billionaire.

Cuban did eventually revisit basketball, buying the NBA's Dallas Mavericks in 2000. He sold his majority stake in the team last year for $3.5 billion, retaining a minority share and control of basketball operations.

"The things I ended up being really good at were the things I found myself putting effort into," said Cuban. "A lot of people talk about passion, but that's really not what you need to focus on."

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank," which features Mark Cuban as a panelist.

Want to master your money this fall? Sign up for CNBC's new online course. We'll teach you practical strategies to hack your budget, reduce your debt, and grow your wealth. Start today to feel more confident and successful. Use code EARLYBIRD for an introductory discount of 30% off, now extended through September 30, 2024, for the back-to-school season.