Stop practicing. Put down the violin. Go away from the practice area.
Try this now so you can see how good it feels
Take a deep breath, pulling the breath in through your nose, and all the way down into your belly. Place your hands below your belly button, and feel your belly expand on the inhale.
Take a few deep inhales and exhales. Enjoy the feeling. This is your own personal treasure, your own space and time. Revel in it, enjoy it.
Watch your shoulders. They should stay level. Only the hands should move in and out. If your chest is rising, he is breathing too high. This causes more feeling of anxiety and stress. We want to calm that feeling, so we want to move the breath downward. This is hard to learn at first, but after a few tries, it usually catches on.
- On the inhale, picture the color blue. Picture it filling every area of tension, tightness, soreness. Picture it filling every emotional area of stress, frustration, exhaustion, worry or anxiety.
- On the exhale, picture the color red. Picture it "catching" all the sore, angry, irritated areas of your body and mind on the way out. Feel it emptying your muscles of the tightness and stiffness.
Now, go back to the practice area.
As you prepare to play, breathe in. On the down bow, breathe out. Let the new, expansive, relaxed breath permeate what you are doing. Breathe into the sound, breathe into the notes.
Note the difference this made in the piece you were practicing.
Repeat this exercise multiple times if the section you are working on is particularly difficult or long.
You can do this at night too, when you are falling asleep. That way the next day's practice will be even better, as the mind assimilates what you've learned today.