Just to reaffirm that when I post the occasion adult/violent content on here - it is not to be scary or intimidating, it is to try to make people comfortable with the idea of death. Some of the best violent movies have excellent philsophical themes in them, if you look beneath the surface. If you live your life unaware of the value of each moment - you will live in fear of death. Yet death comes to everyone eventually anyway.
So you can live your life fearing that something bad might happen, or you can live your life and just deal with whatever comes your way.
Your thoughts are of your own mind and making. If they are making you behave irrationally in any way, it is okay to tell your brain to shut up. If it won't shut up - purposefully distract yourself with something. I find just laying down in the dark, de-stimulating myself to be comforting when anxious.
Grab life by the balls, is a proverbial favourite of mine.
I know I have said this before but it rings true more than anything else and so is worth repeating.