Burnout is a is the hairy-legged spider of the working world. It doesn't just appear in your face, it slowly creeps up on you when you are busy focusing on something else, all the other things. And it leaves you shuddering and shaking with fear and disgust for ages afterwards.
I might be being mildly facetious (although spiders = UGH, amiright?)thing; it creeps up when you are least expecting it and suddenly