One of the skills I teach at every grade level is positive self-talk. I really like counselor Sara Parker's Annoying Nonsense Thoughts.THe book teaches children to turn negative thoughts into a HAWK thought: Happy, Awesome, Wonderful, Knowledge. This is a good general self-regulation skill and especially good for children who are frequently anxious or angry. Her website has terrific ideas for counselors and parents www.friendshipcraze.com She also leads MindUp groups (the program we use at our school) and uses DBT with adults. She has another book P.E.S.T. that you will want to own as well.