When we're down in the dumps, it's hard to image how it could get worse. Of course, if we were rational, we'd evaluate what got us here in the first place, and ask, "How could that make things worse?". Typically, answering that question allows us to see how we can make things get better.
The same goes when things are on the upswing. Asking, "What got us here?", usually helps you answer, "What will get us further?" Usually, they aren't the same thing.