Defunct truism attempts to reestablish former status

I had lived for years with the helpful truism that "whatever you think won't happen". My best friend and I in high school made a habit of thinking of the worse case scenario in order to prevent it from happening. However, a couple of years ago the truism failed me and I relegated it to superstition status. So with regard to yesterday's fight, there was none. In fact I think the whole issue is out of my hands. I'm not ready to begin using it as true, but I may try it out about some upcoming events.