Pessimism is a GIF loop, but not the one you want to experience over and over again. Said cognitive psychologist Amos Tversky: “when you are a pessimist and the bad thing happens, you live it twice. Once when you worry about it, and the second time when it happens.”
Pessimism, like coercion, is natural. It's optimism that's artificial because progress is never permanent. Bad and good things happen in cycles.
Setting realistic expectations balances both outlooks. It prevents pessimists from living bad things twice and stops optimists from gambling. One must toggle between the light and the darkness.