Got a little kid who can’t let little things “roll off her shoulders”? Grab a small soft ball and tell her to pretend that the ball is the annoyance–the pesty sibling, the dog, her anger that you’re out of Lucky Charms and she’ll have to eat eggs and toast and strawberries. Then ask her to stretch her arms to her sides, even with her shoulders, and lean slightly to the right.
Now roll the ball across her shoulders, shift her right shoulder down and let the ball fall to the floor. As you do this, say a short key phrase that’s easy to remember, like “Let it roll” or “Let it go.” This helps her imagine “letting something go” in a concrete way. And it’s funny to pretend your brother is a ball careening to the floor–“Whoops! There goes Jack!”
Have fun with it! Do it once or twice, as often as you like; eventually you can just say your key phrase in the moment she needs it, a little cue to help her remember to let go of the small stuff.