My T was really helpful at teaching me ways to interrupt the negative stream of thoughts. It was almost like I'd gotten into a habit of thinking certain things over and over -- like my brain was in a rut. When I found myself thinking one particularly horrible thing over and over, I would picture my grandmother smoothing her hand over my forehead the way she did when I was sick. Just stop and think of that for a second. The horrible thoughts would come back, and I would think of my grandmother's hand again. It sounds silly and too simple, but it was really helpful to me.