Books to become less pessimistic?

The fking degeneracy of individualism. Look beyond just yourself.

The point of your existence: To be passed, to carry and to pass on the torch of humanity in time until the day we as a race either go extinct or achieve dimensional transcendence. We are each but miniscule cogs in a self-developing machine who are both very insignificant, yet absolutely vital. This should be the ultimate truth.

Everything, including life itself, is equivocal. Fire warms us and cooks our food but it can also burn. Water refreshes us but it could also drown us. Rain and snow can be very unpleasant but it also nurtures the crops and fills the fresh-water rivers vital for our continued survival.

Don't limit yourself to seeing just the negatives of the world you live in. Take all of it in. That's a first step to being less negative. The next step after taking it all in is being thankful for what's good.

If you have any further concerns over existence and death then in a self-conscious manner; for the sake of inner-peace, adopt a faith that promotes a good afterlife and places significance on your existence.

Meditations by Marcus Aurelius
Discourses by Epictetus
Letters from a Stoic by Seneca
Sonnets of William Shakespeare
This is all I can think of at the moment, what is bringing you down?

Leibniz

difference & repetition

read schopenhauer

Fooled by randomness

It's mostly about markets, but will help you realize how huge luck is and how psychologically prepare yourself to deal with it. I remember one passage that likened price moves to mood swings. If the price drops 50%, you need +100% to return to the previous level. The general idea of that negative movement is weighted exponentially greater than positive movement, and that it is far more effective to avoid negative than it is to pursue positive. By focusing on avoiding negative, when positive does arrive you feel lucky, since you just stumbled upon it. Both positive and negative have a snowballing effect, and just keeping your negative snowball small will let your positive snowball roll

Yes.

Steven Pinker: Better Angels and Enlightenment Now.

What the fuck
How

(you) can't handle the truth!

We are cast upon this hellish realm solely for the purpose of struggling and being in pain, so that we may rise stronger each day and carve the world in our image, so that we can finally manage the pain and be proud of ourselves, as the eternal game to ease the pain for generations after us continues.

The Kierkegaard Trilogy

pretty much just face the beast head on.

>adopt a faith that promotes a good afterlife
How is this even possible? Either you believe it or you don't.

To become less pessimistic is to realize the reason why you are pessimistic: (ir)religious existentialism might help you with this.
If you are religious, listen to what () has to say, but if you are irreligious and unfaithful, then don't let the temptation of an afterlife fool you, it is a dominant reason why unfaithful people have become pessimistic in the first place.