Summer is well underway, and it is prime time for travel and vacations. And yet, most people won’t take advantage of the plum opportunities at hand.

According to a new study from LinkedIn (msft), most employees said that success in their careers really means being able to spend time with their families and disconnecting from work. But nearly 70% of employees still don’t disconnect from work email or communications while on vacation.

The most common reason? They don’t want to fall behind, as cited by 56% of the survey’s participants.

This problem is paramount for at least two demographics. First, just five percent of those who identified themselves as “business leaders”—defined within the study as business owners and C-Suite employees—said they “never” check email when on vacation compared to the 30% of workers overall who said they stay unplugged.

And then there are the millennials, roughly defined as those born between 1981 and 1996. According to LinkedIn, most millennials “have vacation request anxiety.” Approximately 16% of the millennials in the survey said they didn’t use their allotted personal time off because they were too nervous to ask for it. The same could be said for a small sliver of Baby Boomers and members of Generation X, but only 6% and 7%, respectively.

But this is just the breakdown by generation. When you look at the workforce more broadly, the problem still exists as the majority (51%) of respondents said they did not use all of their allotted vacation days last year (51%), citing they had “too much work to do.”

“You’re not alone if you feel guilty before asking for time off or shutting down your email on the beach, but you should ask,” Blair Decembrele, a director and career expert at LinkedIn, tells Fortune. “It’s important for your well-being, and we often hear that taking time off makes people more productive when they come back.”

This isn’t the first study to find that not taking a vacation actually hurts, not helps, productivity—and your career. Frequent travelers have reported a higher likelihood of receiving a raise or bonus compared to those who don’t take vacations, according to Project Time Off, an initiative by the U.S. Travel Association that says it wants to remove the stigma for Americans from taking their vacations. The organization also found that employees who use little to none of their vacation time for travel were five percentage points less likely than those who use all or most of their vacation time for travel to receive a raise or bonus in the last three years.

Furthermore, the LinkedIn survey found that when people haven’t taken vacation in three months or more, they admitted they most often felt overwhelmed (58%) and disorganized (21%).

Decembrele has some tips for working up the courage and energy to take vacation. Given the stigmas and fears already acknowledged in these surveys, they might seem easier said than done, but just looking over your company’s vacation policy could be a place to start.

“It may seem simple, but the sooner you request the time off, the less of a surprise it will be for everyone on your team,” Decembrele says. “Before asking for time off, make sure you set a plan in place for the time you’ll be out of the office to set everyone up for success. If your boss knows you’ve delegated the work and arranged coverage, you both will likely feel more at ease taking the time off and disconnecting knowing things will be handled.”

Yet some of those who do use their vacation time might not be actually using the time for rest at all. LinkedIn found that 71% of employees now have a “side hustle,” and among them, 40% have used allotted time off to work on these extra endeavors. While it should be stressed that real time off from work and vacations promote productivity and better health in the long-term, ultimately, it is up to employees as to how they choose to use their time. LinkedIn found that at least one-third (36%) of these workers said they found success by pursuing a passion project.

Consulting firm Censuswide conducted the survey on behalf of LinkedIn. The study was conducted online within the United States between June 22-25, 2018 among 2,169 U.S. adults, aged 18 and higher, who identified themselves as full-time permanent employed, full-time self-employed, or freelance.