I can have anxiety just out of the blue....I have lost that ability to control it but I am learning to get it back .
I am reading this book on Mindfulness called" Calming your anxious mind" and it says how mindfulness & compassion can free you from anxiety, fear and panic.
It teaches you to live in the moment intead of past or future because we can change neither.

It is a book worth reading...in my oppinion.