Deep breathing is a simple exercise that can be used to manage stress and anxiety. Use this video to help teach, and then practice, how to use the technique.
We suggest that therapists work with their clients to identify specific warning signs and situations that indicate a client should practice deep breathing. Additionally, without practice, most relaxation skills will be of little help in a truly anxiety-producing situation. Establish a schedule for your client to regularly practice deep breathing. Some clients might find it helpful to practice for a few minutes at the beginning of each therapy session.
Source :
https://www.therapistaid.com/therapy-video/deep-breathing-exercise