Last night I was reading in bed while the boys finished playing and settled down. Bug (3yo) brought a hard boiled egg yolk into his bed and smashed it on the sheet. (He has hard boiled eggs on a low shelf in the fridge and free access to them anytime he wants.)
I got really grumpy. I was ready to just lay there and read my book until I turned it the light. Changing sheets is one of my least favorite activities. So I'm grumbling and saying things that don't really need saying and so forth.
Josh (9yo) came over and have me a hug saying "I'm sorry you're grumpy mom, but you don't have to be. Everybody feels grumpy sometimes, but they can choose not to be."
I said, "You're right," took a deep breath, and got over myself. It felt wonderful.