Anxiety is caused by a shock of fear to the nervous system. A warning of danger. After the shock, worry of similar thoughts or having another experience causes it to kick in again. It becomes embedded in the memory. Then it is triggered over and over with worry and fear reinforcing it. The way to be free of it is to understand that it is being triggered by the imagination. In other words, it is an illusion. It is only in the persons thought process. In reality, nothing is happening. There are meditations that can get rid of it. There are affirmations that can remove it. Hypnosis can also remove it. The subconscious and the emotions have to be re-trained to stay calm and remain poised regardless of the world and what others are doing. Basically a change in perception or understanding is required to eliminate fear. To see people and the world as it is, not as one thinks or hopes it should be.