We grossly overestimate the length of the effect of misfortune on our lives.
-Nassim Nicholas Taleb, the Black Swan
Humans are the outcome of blind evolutionary process that operate without goal or purpose. Our actions are not part of some divine cosmic plan, and if planet Earth were to blow up tomorrow morning, the universe would probably keep going about its business as usual.
Hence any meaning that people ascribe to their lives is just a delusion.
So perhaps happiness is synchronising one's personal delusions of meaning with the prevailing collective delusions.
- Yuval Noah Harari, Sapiens