Stephanie Heredia’s promotion came a year too late and more than a few dollars short. Heredia, 29, started an accountant job at a small Tampa, Florida firm, with the promise that her $60,000 base salary would rise to $100,000 after one year.

But at the last minute, she told Fortune, the timeline became two years. Her eventual salary—$90,000, plus commissions. As the firm grew from four people to 25, Heredia’s responsibilities ballooned. She was charged with opening a new unit in Puerto Rico, which went on to generate an additional $2 million annually for the firm, but asking for a raise felt “like talking to a brick wall,” Heredia said.

“I’d have sales over $300k annually but was only making $90k while doing ALL the work of the clients I brought in [and] the other work at the firm,” Heredia said, adding, “I sadly have way too many spreadsheets comparing the money I was bringing in [versus] bringing home!”

“I was starting to realize I was burning out pretty quickly,” she recalled. “I made the decision that I couldn’t keep building someone else’s dream.”

Heredia is far from alone. Workers promoted into management positions are increasingly under stress, new research shows. Indeed, workers who get their first promotion into management are more likely to leave their employer immediately after, compared with workers who don’t get promoted, according to recent research from payroll processor ADP. And a Gallup poll last week found that managers are more likely to be burned out or disengaged than workers overall.

“[B]eing the boss usually comes with its perks. Unfortunately, today it’s mostly just a tough job,” Gallup concluded.

Nearly two-thirds of poll respondents said their job responsibilities increased, while 42% said that their budgets had been cut. Perhaps not surprisingly, a majority of managers are currently looking for new jobs, Gallup found.

For Heredia, it was right after she had made the decision to leave that her long-awaited promotion came. Her boss called her into his office and offered her a promotion to partner, complete with a stake in the firm.

This would bring her total salary to $120,000, but she would no longer be eligible for commissions—meaning her total compensation would be cut. Still, Heredia said she accepted out of exhaustion. “I had worked so hard that I thought accepting would undo my resentment and make me whole again,” she said.

It didn’t. Six months later, Heredia started her own firm, Taxes Tampa. A year after leaving, she insists she has “never felt better.”