You can change your shallow, short breaths, in stress and anxiety by controlling your breathing, with slow, deep, peaceful breaths.
“Have you noticed that when you’re deep in thought, focused, concentrating intensely on something, your breathing is deep and slow? When you are anxious and excited your breating is shallow and fast paced. When you’re shocked, frightened, or extremely angry, your breathing may actually stop momentarily. But if you deliberately take control of your breathing and slow it down, your mental or emotional state will start to calm down. When you deliberately slow your breathing, you’re taking control of your mind and energy.” by Author Dr. Tae Yun Kim, in The Silent Master ebook, pg 73