Take a partner or better yet your child and sit or stand comfortably with them. Relax your eyes by avoiding focusing on one thing or traveling from one thing to another all the time and see his chest and throat move with the breathing. Observe for a while and than start to breathe with him and follow his changes in breath. Feel if there is a difference in your interaction and than with your partner or if your child is grown enough work on a drill like take downs or hitting and while you do this observe the breathing again and note to yourself how this works for you.