Books to help with being more optimistic?

I've always been a pessimist since I was young and I think it was more of a coping mechanism to assume the worst case scenario and accept it before anything bad happens. Maybe over the years this sort of negative thinking has made me inadvertently manifest these bad things? My friends who have always been optimistic have got the opportunities they wanted and these examples around me are making me curious about shifting my mindset to be more optimistic.. I tried being more positive but the science doesn't really add up in my head so I need some push and some philosophical/science based facts to back this would help to an extent.

Just curious if any of you have found books that help to lean towards more hopeful and positive thinking. Also open to reading fiction if it's made an impact for you.