Reading science fiction is one of the surest ways to achieve a healthy sense of perspective. Few other genres take you so far outside the context of your immediate reality while still remaining grounded in the plausible.
The last three novels I read–re-read, in fact–were the trilogy of Manifold novels by Stephen Baxter. Each deals with timescales reaching out to the end of the universe. But more important than plain cosmological speculation is their description of human purpose within those vast timescales. Science fiction stories do not just expose you to big ideas, they infuse those ideas with personal meaning. And when such ideas become not just interesting factoids and instead develop them into relatable scenarios into which you can inject yourself, or your relationships, or your values, then the perspective shifting begins.
Science fiction works by engendering a greater appreciation of scale. Most general fiction asks you to step outside of yourself. It confronts you and makes you think about the three pounds of brain inside your skull and your miniature network of relationships. What do those things mean to you, when there are so many other ways they could be? History, if you listen to its narratives, already begs you to question the worth of your decades and your values in the face of the centuries and movements of countries and cultures. Science fiction zooms out again, on the order of magnitudes. What is your country, what is your species, what is life, what is your planet, what are all these radically large and complex things, in the face of things infinitely more grand and complicated?
Science fiction provokes moral and normative reflection. If I am so little, if all of my thoughts and experiences and most every human-made thing around me is so seemingly insignificant, then how should I act and how should I be?