When anxiety strikes, strike back. When I was in the hospital, I made a list of little things I could do to preoccupy my mind when I dissociated (a common symptom of PTSD). Sometimes when you feel an anxiety attack coming on, there's nothing you can do to stop it. These are the things I attempt to do to pull me back to reality. They don't take too much concentration but will distract your mind and pass the time.
1. Talk A Walk (or a run)
2. Scribble
3. Take A Shower (hot or cold)
4. Write
5. Color (mandala coloring books are fun)
6. Do Your Makeup
7. Clean Your Room/Do Your Dishes
8. Write A List (of anything! ex: things you find in the woods from a-z)
9. Go For A Drive (if it's safe to do so)
10. Dance Like No Ones Watching
11. Cook Something (even if you have to save it for later)
12. Call Someone To Chat