Deep Breathing is probably the most important action one can take toward reducing anxiety. It's also the one that gets the most eye rolling from my clients when I suggest it. The two stories from NPR give very good evidence for using deep breathing as a healthy way to relax.
Many of us go through the day with an internal dialogue or voice narrating or play calling our life. When our mood takes a negative turn the narrative in our minds often follows. I’ve often told my clients that the upper cognitive part of the brain and the lower emotional brain want to be in sync. So when one takes the lead the other follows. Chicken and egg aside, if we are feeling down and depressed our thoughts begin to match that feeling.