The ultimate value of the "negative path" may not be its role in facilitating upbeat emotions or even success. It is simply realism. The future really is uncertain, after all, and things really do go wrong as well as right. We are too often motivated by a craving to put an end to the inevitable surprises in our lives.
This is especially true of the biggest "negative" of all. Might we benefit from contemplating mortality more regularly than we do? As Steve Jobs famously declared, "Remembering that you are going to die is the best way that I know to avoid the trap of thinking you have something to lose."
Stoics rule! --ts