try some mindfulness techniques of just recogniziing the thought and then just letting it go...see it as a cloud just floating through your head..in the front door of your mind and out the back...you can read a lot about mindfulness techniques on the internet. the in the front door and out the back visualization works best for me. i actually see the thought marching through my brain and then kicking it out the back door. it gives me just enough time to dwell on it. good luck.