They're called "work martyrs." They're the ones—and statistics indicate that they represent 40 percent of the American workforce—who contribute to nearly 430 million days of unused paid vacation a year.
In a report entitled "Overwhelmed America: Why Don't We Use Our Earned Leave?", analysts found that millions of Americans worry about the possibility of taking time off and returning to a mountain of work. And more than a third said they didn't take a vacation because they felt no one else could do their job. Interestingly, one-third also said they didn't want to be seen as replaceable.