If you're not planning to take time off this summer, here's some advice: do it.

A new study has found that the US leads the world in unused vacation days. Collectively, we don't use 429 MILLION days each year. That's a lot of missed "Are we there yets?"

On average, workers fail to take 3.2 days annually, while 40% of those with jobs failed to take all the vacation allotted to them last year.

It's certainly okay to work hard, but remember to play hard, too. Or not play at all. Vegging out is cool, too.