You made it through the whole workday. You responded to every email with appropriate punctuation. You laughed at the right moments in the meeting. You nodded along when someone told a long, winding story that had no point. You said "sounds good!" when nothing about it sounded good. And then you got to your car, sat down, and couldn't move. Not tired. Not just tired. Something heavier than that. Something that doesn't fully go away after a good night's sleep or a weekend off.