Somatics (in the tradition of Thomas Hanna) teaches you how your posture is an expression of your nervous system and gives you a doorway into understanding how stress and anxiety affects you, not only mentally and emotionally, but physically too.
Our nervous system is constantly stimulated as it filters our senses, through what we see, hear, and feel. If those senses are stressful or fearful, the fight, flight and freeze responses are triggered. If triggered continually these responses become habituated, physically changing our posture.
Thomas Hanna codified these responses into the Red and Green Light reflex patterns. He created movements and techniques to release out of each reflex, so the starting point is to learn to sense these reflex patters in yourself.