It's hour ten of the wedding and I've been warm and smiling the whole time, even after a guest yelled at me over the seating. Inside I'm completely empty, but the bride is walking over with another problem. I have to be 'on' for three more hours, and there's nothing left in the tank.
More people experience this than they realize.
You have to keep giving warmth to everyone long after you feel emptied out.
If this sounds familiar, the Library can help you find the bigger picture.