Even if you are able to keep from moving you will still communicate rigidity, anxiety, or something. We are always saying something. It is important to observe and try to understand what is being communicated. In many situations people say what they think intellectually rather than what they feel emotionally. Body language, carefully observed and interpreted, can tell a lot about what others are feeling.
Nonverbal communication is learned and practiced often on an unconscious level.
As we grow older and become more aware of ourselves we should be able to recognize and weed out the unwholesome in favor of those for whom we have an affinity. Body language can be disguised behind a mask out of a fear of rejection. This can discourage wanted and needed relationships from developing. Those who want and need certain relationships to develop must relearn their nonverbal skills and unmask themselves in order to avoid alienation. Body language is open to misinterpretation just as verbal communication is.