If someone at the office is making you feel consistently drained, stressed or unmotivated, you might be dealing with a toxic coworker.
That's according to Stanford University professor and bestselling author Robert Sutton, who's devoted years to the study of mean employees.
"Over the course of our lifetimes," he tells CNBC Make It, "about 50 percent of us will face persistent bullying or observe it regularly in the workplace."
So how do you deal with this type of coworker?
Changing how you react mentally, or using psychological tricks, can significantly help, says Sutton, organizational psychologist and the author of "The A-----e Survival Guide."