A report from Project: Time Off, an organization started by the U.S. Travel Association to change American work attitudes and behavior, says increased work pressures and a 24/7 always-on attitude have caused many Americans to increasingly abandon their vacation days. It's estimated that 55% of working Americans didn’t use all of their vacation days in 2015, leaving behind 658 million days of unused PTO. The decline in vacation day usage began in 2000, just as the oldest millennials—those born around 1980—started to enter the workforce. Project: Time Off’s report, The Work Martyr’s Cautionary Tale: How the Millennial Work Experience Will Define America’s Vacation Culture, says that the youngest generation in the U.S. workforce has created an era of work martyrdom, prioritizing work above family and personal happiness. Katie Denis, senior program director of Project Time Off, tells Travel + Leisure that “Four out of every 10 employees say they actually want to be seen as a work martyr by their boss. But at home, it is a different story - 86% of employees believe it is a bad thing to be seen as a work martyr by their family.” Get the full story at Travel + Leisure