Are there times when optimism can be bad, or pessimism can be good?

I believe that in fact being optimistic is a good way to manage your life because you try to see everything that happens in your life with a good mood, also being an optimist can help you to keep your mind at ease. On the other hand, being a pessimist always causes stress and doesn't allow you to have the life that all being humans need to have, and sometimes people believe things that only exist in their minds and doesn't exist. Certainly, there are times when being an optimist doesn't help you because it makes you believe in something that maybe won't (better: might not) happen and create a false expectations (in a person). Finally, I don't think being a pessimist is good. I just believe that if I'm believe in myself, possess self-esteem, self-confidence and do things correctly, I will be an honest and humble person who only believes things for a reason.

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Well done!

(an) optimist, (a) pessimist, optimism, pessimism, humility => nouns

optimistic, pessimistic => adjectives

correctly, honestly => adverbs

think = pensar / believe = creer

stuff => slang, avoid using this word in writing