What to do when you are scared

I am undertaking some self defence training - The Golden Canes program.  Here is a gem from the program, not just a habit of the week, but a habit for anytime.
When we are scared, really scared, almost automatically take a breath in, and then hold our breath. Instead, put the tongue on the roof of the mouth, and exhale.  The exhale has a calming effect and thus gives us some control back and switches our brain back into thinking and creative mode. So we can make a plan to get out of danger.  The tongue on the roof of the mouth completes a loop of our inner energy, some would say, our chi, and in the event of an impact or a fall we don't bite our tongue.

This is an easy and instant response to fear.  I have started practising already.