Wish for things to be as they are, and life flows easily.

Where this comes from

Epictetus taught that much of our unhappiness comes from wanting things to go differently from how they are going. This line from his handbook, about 1,900 years old, is his answer: want what is actually happening, and life gets easier.

How you could say it to a five-year-old

“You wanted the red cup. Your sister has it. Today is a blue cup day.”

Epictetus, Enchiridion 8. We put these lines into plain English ourselves, staying close to the original and to public-domain translations.