smile! Also I will do a little bit stretch while brushing my teeth as it keeps me from boring. Another interesting way is to use the hand tou don't use usually, it will keep you to brush more carefully and train your other side of brain that you don't use a lot.
Must brush in circular motion for the front facing teeth and then brush in a long time. The inner side of teeth must brush upside down for upper and lower teeth and then rinse the toothbrush