A character feels insecure about their height. Being upset about their height. Height has a lot to do with how someone interacts with the world. Since people base a lot of first impressions on appearance a height that contrasts with what someone wants to look can cause them to be angsty, which can be expressed in different ways. "I remember when everybody was my size. Boy, was that great! But then everybody started moving up, and there I was, stuck at four foot ten..."