Millennial workers are the most likely generation to forfeit time off, even though they earn the least amount of vacation days, according to a report released today by Project: Time Off. The survey found millennials stay at work because they feel more fear and greater guilt about taking time away from the office than any other generation.

Compared to those in the boomer generation, millennials are at least twice as likely to find taking time off difficult because they don't want to lose consideration for a raise or promotion, don’t want others to think they are replaceable, and want to show complete dedication, among other reasons.

The report also found 28% of millennials hold management roles, and nearly half of millennial managers, 47%, said that company pressure prevents them from approving time off requests for their direct reports, compared to just 34% of Generation X and 37% of boomers who feel the same.

“The ‘entitled millennial’ narrative is dead wrong when it comes to vacation,” said Project: Time Off Senior Director and report author Katie Denis. “As the largest generation in the workforce, one that is now stepping into management, millennials are developing vacation attitudes that will define and negatively affect America's work culture. The circumstances of the millennial experience — the Great Recession and its aftershocks, growing student debt and an always-connected lifestyle — have created a perfect storm for their work martyr behavior.”

GfK conducted the online survey from Jan. 20 to Feb. 16, 2016. It included 5,641 American workers working at least 35 hours per week and who receive paid time off.