I found this several years ago. It is from the pen of Dr. Daniel Amen, and has helped me in my quest for distinguishing truth from untruth. When I apply these questions to something I am contemplating, it becomes much simpler to sort out my thoughts.
(1) Is this thought true?
(2) Can I absolutely KNOW that this thought is true?
(3) How do I feel when I believe this thought?
(4) Who / What / How would I be without this thought.
Then I force myself to turn the idea around – stand it on its head, by asking myself…
(5) What would be the opposite thought to this one?
(6) Could this new thought be as true or even truer than my current thought?