I drew this cartoon as a reminder: your thoughts determine experience.
Everything that happens to you happens through the filter of your mind. If your mind is clogged with pessimism, fear or hopelessness, possibility trips over these before anything good can happen.
Optimism is incredibly important because it's a foundation for hope, creativity, and will.
If people are in charge of driving their experience, and not victims of chance, optimism is a need, and not a want. Cultivate some today, by observing any pessimistic thoughts, and asking yourself where they're going.