I have generally tended to spend too much time trying to plan against negative scenarios. Seems like a good thing, to "be prepared", and all. But if the events aren't very likely, it's a waste of time and attention that could be better spent elsewhere. Perhaps worse, I think it distorts one's view of reality by the availability heuristic, so that the world seems more threatening than it is, so that I ended up not just feeling like the world was worse than it was, but acting on that inaccurate model of the world as well.

I try to remind myself to always estimate the likelihood of the bad thing happening, and if it's small enough, to let it go.