Not a book. But a game. Scratch that, it is meditation, a life lesson and an existential crisis packed into a computer program. But I'll call it a game since it's convenient.
Outer Wilds.
Mechanically, you play as a space archaeologist stuck in a time loop. The whole game is a giant knowledge puzzle, and you explore an entire solar system in search of clues about a long-gone civilization.
If this sounds even remotely interesting, stop reading and go play the game, because every bit of information is a spoiler, and below I'll talk about my experiences about it. Seriously, do not watch any gameplay, just make sure your computer meets the (rather tame) requirements, buy [0] and play it, then you can come back.
---
It is not a motivational game. It doesn't have a point to make. Instead, it confronts you with an entire way of existence and makes you ask of yourself what you make of it, and any takeaways will be incredibly personal. Heck, even if you don't discover any intuitions, it's still an intrinsically fun experience that perfectly exercises the "nerd curiosity" (or "The Knack" as it is put in Dilbert [1]).
The game starts out as this vaguely giddy space adventure, but as you come to understand the Nomai, it instills in you so much true awe: The perseverance of these people, to settle in the galactic backwoods in search of the answer to the Universe. The melancholy of a people who achieved the pinnacle of technology, sure of their destiny, only to be destroyed oh so early. The incredible anxiety of living at the end of the Universe, where the only way out is to deny yourself of existence.
After wandering space for who knows how long, piecing together this intangible society and their long-overdue plans, while the rest of your kind seems to be on the spacefaring equivalent of a holiday break, you come to appreciate every little interaction with the present. This feeling is more welcome as you unfold the story, but you know it is empty time, so like the Nomai before, you must persevere, and solve the Universe. The consequences will be dear, but inevitable. The Universe is waiting on you.
For me, having played this game this game gave me a perspective to truly appreciate what I have, and the moment I live in, even despite all that is going on and how things seem to be going sour. It also rekindled my interest for discovery for discovery's sake, and, in a way, gave me peace towards the idea of death. It also gave me many perspectives about myself which I don't need to share online, but were really appreciated.
And then...
They made an expansion [2], which resolves the only remaining plot point of the story beautifully, and while it is more traditionally "puzzle"-y than the base game, is a great excuse for a replay, and gives you a new friend to mourn.
Just like in the base game, we had the naively curious Hearthians, and the incredibly rational Nomai, here we see a third take on the events of the game: An entire race of heartbroken people, who unlike the Nomai, seek to deny everyone from the answers seeked in game.
---
[0]: https://store.steampowered.com/app/753640/Outer_Wilds/ also available for consoles.
[1]: https://www.youtube.com/watch?v=g8vHhgh6oM0
[2]: https://store.steampowered.com/app/1622100/Outer_Wilds__Echo...