This title is taken from the poem of the same name by Erma Bombeck (poem copied out in full below). It is a title that says everything - Erma wrote this on learning that she had a terminal illness. What are the things that really matter to us? What are the things that left undone would not have mattered but we made them matter, foolishly believing that worrying and beating ourselves up somehow achieved something? Try something today. Instead of worrying about some small thing, either laugh it off and forget it totally, or ignore it completely.