If the anxiety is new, you might also want to check with a doctor to rule out a physical ailment as the cause of the feeling of anxiety. Sometimes the mind gets involved when the body is out of whack.
Otherwise, I personally find music helpful. Think of a song you find relaxing and try playing it in your head.
Hope you feel better soon!
Have you tried therapy? Positive thinking? Read any books on anxiety disorders? Seen a doctor? Try to keep busy and find a hobby. This personal helps me. If I don't stay busy my anxiety with kick in! Of course I have my leisure time and relax, but I try to keep my mind busy