You can come up with a coping statement - like "I am ok, this may be difficult, but I will get through it. If I am rejected it is not the end of the world. Most people will not reject me" or whatever your particular issue is.
One my therapist taught me that I like, that is so so simple is to just repeat "I'm not going to let the SA win anymore. It has taken too much of my life, and I'm not going to let it win". Helps me snap out of my own world before I go into a tailspin!