Why do good employees leave? Is it the money? A new challenge? Better coffee in the break room? Chances are, it’s management.

A recent Gallup research study says 70% of an employee’s motivation is influenced by his or her manager. A separate study of more than 50,000 workers by the Corporate Leadership Council said properly motivated employees are 87% less likely to quit.

“Managers tend to blame their turnover problems on everything under the sun, while ignoring the crux of the matter: people don’t leave jobs; they leave managers,” wrote Dr. Travis Bradberry, co-author of Emotional Intelligence 2.0. “The sad thing is that this can easily be avoided. All that’s required is a new perspective and some extra effort on the manager’s part.”

What’s the worst thing bad managers do? They overwork employees.

“Nothing burns good employees out quite like overworking them,” Bradberry wrote.” It’s so tempting to work your best people hard that managers frequently fall into this trap. Overworking good employees is perplexing; it makes them feel as if they’re being punished for great performance.”

Read Bradberry’s full article here for other things bad managers do to make good employees leave.