Americans are overwhelmed—but they aren’t taking the breaks they’ve earned. Nearly three-quarters of workers say they are stressed at work, with one-in-four reporting they are either “very” or “extremely” stressed.

It’s no surprise that Americans feel this way. Many workers leave their paid time off (PTO) unused, despite near-universal recognition of the importance and benefits of using PTO, from reducing stress to improving productivity when we return to work.

But when the U.S. Travel Association asked GfK Public Affairs and Corporate Communications to examine the attitudes and beliefs underlying America’s hard-charging work culture, GfK discovered that the benefits of PTO were no match for the fears that are keeping them at work.

In a survey of more than 1,300 employees and senior business leaders across the United States, it was revealed that workers construct many of their own biggest barriers to taking time off. Returning to a mountain of work and the feeling that nobody else could do their job were cited as the top reasons for not using PTO. The effects of a tough economy still linger with one-third of respondents, who said they cannot afford to use their time off, and roughly a fifth of workers expressed concern that they would be seen as replaceable if they used their PTO.

I am lucky to have a job that offers a lot of PTO as well as "sick days" that carry over year over year. I think I have hundreds of sick days compiled and about 4 weeks PTO. I'll likely not take all of my PTO this year and it's for some of the same reasons listed in this report. If I'm not working, I'm not making $. That simple.