I have Post Traumatic Stress Disorder which is classified as an anxiety disorder. This disorder goes into a number of issues that range in severity. After struggling for awhile, I adopted a new life philosophy, "STOP THINKING!". That may sound silly, but it helps in all aspects in my life. If you can't control something, throw your hands in the air and say "fuck it!". I promise your stress levels will plummet.
On the money, I get pretty bad anxiety and just have to remind myself that what happens, happens.