Here's an image for you. Think of your anxiety as a cute & harmless little monkey sitting on your shoulder. This monkey is very frightened, and it keeps on whispering in your ear ("What if such-and-such happens"). Whenever I have a scary thought or idea ("What if I start panicking?" "What if..."), I follow a simple process: (1) I remind myself that's it's just 'Monkey Talk', and the Monkey is very scared and should never be trusted (sometimes I say "Monkey Talk" out loud, very quietly to myself, to remind myself of this!); (2) I identify the 'triggers' (Have I been isolating recently? Am I tired? Have I been taking stimulants recently, such as caffeine or alcohol? Have I eaten? Am I in an anxiety-creating environment? etc.); and (3) I, finally, I get "busy busy busy" and resolutely turn my attention elsewhere.

By externalising my anxiety, and seeing it for what it is (it's my subconscious fear speaking, nothing more), I find I can distance myself from it.

Sounds nuts perhaps, but it works.