This is a basic explanation of some of the science behind what happens in the brain and body when we experience anxiety. There is so much more to it, but understanding these basics can help you begin to look at what is happening in the brain so you can shift thoughts from uncertainty, fear, and discomfort to acceptance. Not resisting the uncomfortable feelings associated with the thoughts all while accepting the thoughts as probably false, distorted and unrealistic can ease your physical and psychological symptoms.
This is called anxiety management. It is also called brain training or cognitive behavioral therapy. It works with practice and persistence.