FEEL PESSIMISTIC ABOUT can be summed up as having a feeling of DOUBT or uncertainty. DOUBT is a common emotion that is often associated with pessimism, and it can be caused by a lack of knowledge or understanding about a certain situation. It can also be caused by a fear of the unknown or a fear of failure. When someone feels pessimistic about something, they may feel overwhelmed or helpless, and this can lead to feelings of hopelessness.