As a child, I loved the Disney movie Pollyanna starring Hayley Mills. It's about a little girl who goes to live with her rich aunt Polly after the death of her father. Pollyanna brings hope to everyone around her by playing a game her father made up - The Glad Game. Pollyanna's father was a missionary. When the missionary barrel came, Pollyanna had hoped to find a doll inside, but what she found was a pair of crutches. She was horribly disappointed. So her father made up the game. He said it was always possible to find something to be glad about. In regard to the crutches, Pollyanna could be glad she didn't need them.
Last year, I read Pollyanna to my 4th graders, and both the boys and girls loved it. (Its grade-level equivalent is 5.8, its Lexile is 870, and Scholastic lists its interest level as grades 3 through 5. Ambleside Online includes the book as a Year 4 extra.) It's a sweet book, and I highly recommend it.
In another book on optimism - Learned Optimism - the author Martin Seligman writes that problems are temporary, external, and specific. With my daughter (three years old tomorrow), I remind her that problems are fixable (temporary).
POLLYANNA: There are eight hundred happy texts, did you know that?
REVEREND: No, I didn't know that.
POLLYANNA: Yes, well there are. And do you know, my father said that if God took the trouble to tell us eight hundred times to be glad and rejoice, He must have wanted us to do it.
-from Disney's Pollyanna (1960)