I am not sure that we have the option to be an optimist or pessimist. To be one or the other seems to be more a habit that is hard to break. I suppose that a life of bitter disappointments could have something to do with which way a person leans

Agreeing that we still have much work ahead is not necessarily pessimism. It is just realistic. I am optimistic that the nature of mass human consciousness is far more good than bad when it is not overtaken by religious or political dogma. I am optimistic that most of our leaders live more in the light than the dark.

Anyway, I am usually optimistic and I am rewarded often enough to make me happy with that state of mind.