I question whether they're realistic or if I'm just being dramatic. Usually, they're the latter, so I try to be more rational with myself. I try to remember that negative thoughts don't really accomplish anything for me. (this doesn't always work, but I'm working on it)
I write them down on a piece of paper, place them inside a pair of socks and wash them. By the time they reach the washing line, I'm more worried about what's for dinner.
invite them in, take care of them, give them some nourishment and entertainment and when necessary escort them to the way out when they start to intrude too much.