Leo Tolstoy suffered over the same question: "I am a man, how should I live? What do I do?" His non-fiction on the very topic contains the very simple answer, thats been right there under our noses all along: love (selflessness), but it's become easy to miss due to its disguise of spiritual/supernatural this or that and incessant answers to the ideas of a God and an Afterlife—opposed to the value and capacity of our inherency to selflessness—being held as unquestionably true via these influences, only blinding the masses of the truth that's hidden underneath all the dogma.
https://www.themarginalian.org/2014/06/03/tolstoy-confession/
His non-fiction he wrote on his long quest for truth: Confession, What I Believe, The Gospel in Brief, and The Kingdom of God is Within You.
Some translations can be a bit of a chore to read, therefore I humbly suggest the ones linked below:
Confession: https://www.amazon.com/Death-Ivan-Ilyich-Confession/dp/0871402998
What I Believe: https://www.amazon.com/My-Religion-What-I-believe/dp/B0863TFZRN
The Gospel In Brief: https://www.amazon.com/Gospel-Brief-Harper-Perennial-Thought/dp/006199345X