When I did CBT, the main things my therapist made me do were thought records, and honestly everytime i finished one I saw things for what they were, and with a more rational view.
Here's an example of one from me.
Just copy and paste and fill yours in for you.
See if it helps you atall.
Make a point of seeing things from a different view i.e almost like your arguing both sides of a case. Read back what you wrote and come up with a verdict. It can be as long or as short as you want. Just give it a try.
My Main Worry: My heart, dropping dead from some sort of arrhythmia, or undiagnosed heart defect.
Facts that support my fear: I get skipped beats, dizziness and sometimes a racing heart, I've been tested but I know that doctors can make mistakes.
Facts against: I've been tested so many times, and have been given the all clear each and every time. My skipped beats are probably caused by anxiety, and dizziness is a major symptom of anxiety too. Doctors do makes mistakes (very rarely) but for the amount of times I've been to my doctor complaining he would surely have picked something up on atleast 1 visit!
Verdict: Anxiety causing my fears/symptoms and putting unsettling thoughts into my head. My heart is okay.
Now you try...