Can a pessimist really become an optimist?

For as long as i can remember i've been a pessimist, to be that makes life easier and i have far fewer disapointments in life, less pain etc.

But i know that i really should try to inject some optimism in my life, problem is i don't have that ability, all i see is the negative side of things because life isn't a fairytale, things never really go the way you want them to, life always loves screwing you over
Can a pessimist really become an optimist?
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