Just relax! That statement has never helped me. What does help? Breathing. In fact, the best breathing exercises I've learned are from singing. Singing is really the art of breathing. Here are a couple breathing exercises you can use to bring yourself in touch with your body again and to find your center.
1. Breathe from your diaphragm. Not sure where it is? When you breath in your lower abdomen should push out and collapse as you breathe out.
2. With your mouth closed, do rapid in and out breaths through your nose. Try IN-IN-Out three times or IN-OUT rapidly for 30 seconds.