You find yourself looking a ball of cat pee in scoopable litter and thinking, "okay, I've got to weigh and chart that."
You wake up from a dead sleep and find yourself bolting out of the bedroom because you hear the "beep-beep-beep" of a truck backing up and think it's an IV alarm, a bed exit alarm, or a vent alarm.
You're finish the postmortem on one patient when a second codes, and the first thing you think is, "You couldn't have waited 30 minutes, could you?"
You want to stand in your unit and wave your arms like an airtraffic controller, saying, "GI bleeds to the right, DTs to the left, MI's proximal, CVAs distal."
When you have a family member spending the night who's asking for everything under the sun -- food, drinks, "change" for the snack machines, fully made out beds -- and you just want to walk in, pull them out of their bed, lay down in it yourself and pull the covers over your head because you haven't sat down for 30 seconds except to pee in the last 11 hours.
When you can't remember the last time you did something that was fun.