The advice that Ceylyn gave was excellent.
Additionally, I recommend deep breathing exercises because they will significantly lower your stress levels and anxiety, too. I get occasonal bouts of anxiety, but it gets dealt with from this lovely easy breathing and relaxion technique my aunt gave. It really is very good!
1. I take a long, slow breath in through my nose, first filling my lower lungs, then my upper lungs.
2. I hold my breath and slowly count 1-2-3.
3. Then I exhale slowly through partly closed lips, while slackening my shoulders to relax them.
Controlling your breathing this way helps bring anxiety right down!
There is another breathing technique I use that could be helpful. This is a relaxation technique that I use when stressed. I particularly like
the colour green; the colour helps relax me.
Choose a word or a phase. Example: Lake; Sea; River; Blue sky; Green fields as far as the eye can see; Twilight, even.
Sit quietly in a relaxing and comfortable position, close your eyes and relax your muscles. Breath slowly, repeating your focus word(s) in your mind as you exhale. If everyday thoughts intrude, let them go and return and continue this for ten to twenty minutes.
I use these breathing techniques any time when feeling suddenly anxious. Also, each time I remember that I managed to endure the last fright-and-flight feeling, it feels like I've becoming stronger. So try these and stay with them a while.
Do let me know how you get on.
Wishing you all the best,
-Belle