I suggest that you practice a breathing technique that suits you whenever you become aware of feeling anxiety.
Basic breathing exercise: Breathe deeply into your belly just above your hips. When you breath in, imagine that the air you breathe is coming from the Cosmos through the top of your head and down into your belly button (Hara Point). When you breathe out, imagine that energy from the Earth is rising up through your feet to your belly button (Hara point). From this Hara Point, energy will be distributed throughout your body, relaxing, healing and energizing you. See also the first video I have sent you the link to below.
Breathing, Hyper-ventilation and Anxiety Slowing down our breathing and breathing more deeply, using our diaphragm, belly, rib cage, and lower back in the breathing process, reduces anxiety. Many of us, without knowing it, habitually "hyper-ventilate"--that is, we take quick, shallow breaths from the top of our chest. This reduces the level of carbon dioxide in our blood causing the arteries, including the carotid artery going to the brain, to constrict, reducing the flow of blood. When this occurs, no matter how fast we breathe, our brain and body will experience a shortage of oxygen. The brain responds to lack of oxygen by activating the sympathetic nervous system "fight or flight reflex" response. We become tense, anxious, and irritable. We become unable to think clearly.
Conscious Breathing For Relaxation and Pain Reduction
Bringing our attention to our breathing during meditation brings many such benefits. Such mindful breathing helps us release peptide molecules from the hindbrain to regulate breathing while unifying body systems. Simply follow your breathing with your attention.
Digestive Breathing Digestive breathing is a simple but effective breathing exercise that can help promote digestion. It is based on breathing deep into your belly. As you breathing in, sense that you are breathing energy gently into your expanding belly. As you are breathing out, sense your belly naturally contracting. Do not use force. Work in this way with your breathing for at least five minutes after each meal, or any time you have digestive problems.
Breathing for Relaxation
Some of us try to do deep breathing when we want to relax. Unfortunately, most of us do not really know how to breathe deeply. We do not know how to release the unnecessary tension in our belly, back and ribs. Emphasize and lengthen your exhalation. It's what happens naturally when you sigh. The long exhalation helps turn on your parasympathetic nervous system, your "relaxation response." There's nothing to do except to make sure your exhalation is longer than your inhalation. Don't worry about the inhalation; it will take care of itself. This breathing exercise can be undertaken safely whenever you feel stress coming on.
Here are some helpful deep relaxation exercises on You Tube such as I might teach you in my clinic. Please choose your favourite and practice a relaxation exercise for at least 10 minutes per day. Perhaps you would enjoy this at bed time.
Simple "Pranayama" Breathing Pattern 4 Stress Relief
http://www.youtube.com/watch?v=NxCkQDDWzww
Progressive Relaxation For Stress Relief & Management
http://www.youtube.com/watch?v=dLEweEr-Ow0
Progressive Relaxation Video under 10 minutes for TUWALKI
http://www.youtube.com/watch?v=-1nJpxoiPjA
Deep relaxation session by LifeCoach ALKISTIS
http://www.youtube.com/watch?v=RkqfXpbyCZg
Guided Deep Relaxation by Mark Saylors and Steve Powers with Native American Flute
http://www.youtube.com/watch?v=r4Jmf7Mo6dA