Interesting thread.
Personally I believe in what my now dead father once told me when as a young man I was worried about the "end" ... of an era, of my body, of the world, or anything angsty teenagers get anxious about when they are young and which happened to me.
He looked me straight in the eye and told me half smirking half despising me:
"Son ... the world ends for those that die ... if you die your world ends, no matter what, so stop worrying about that, its useless" .
Some years up in the future I had to go pickup my brother after being kidnapped and dropped in the middle of a field, had to escape a couple of car thieves shooting at me and smashing my car windows due to the bullets, went to a caribbean island to claim some inheritance and had to flee in the middle of the night with my sister as hired thugs were trying to kidnap us to avoid claiming it and flew off the island next day, went to two funerals of friends killed during robbery attempts , saw my best friends slowly leave my country after close encounters with death/kidnappings/rapes. I eventually had to go into exile as well into a different country and then had to face many other awful things.
My world has been ending for quite a while and not once I worried about the world "ending" because it is pointless for me, though I respect other people that hold that view.
But honestly, after my own tale and seeing my own friends tales (some of them more bloody and sadder than mine , check the Venezuelan Exodus entry for a bit of background
https://en.wikipedia.org/wiki/Venezuelan_refugee_crisis) and you come to a point where you just stop caring about that.
So in a sense you are faced with some limited options>
1- The world is ending due to a Religious happenstance, so the only thing left to do is having lived a good life or at least good enough for you to think you did more good than bad and are free of "sin" or "guilt".
2- The world is ending due to a ELE , same as before with the added tension of having to find refuge and everything in the GREENLAND movie was bogus so no luck there so better end it like KNOWING with Nicolas Cage and embrace your family and loved ones and call it a day.
3-The world is ending because you have a terminal illness and well, you give it a good fight or not, up to you and then accept the consequences and that even no matter what you do you might still die. So make your peace with the world and try to die happy or at least in not much pain and close your eyes
4- Nothing is happening and guess what? Your world will end any day from now so you just focus on doing fun things and try to enjoy your time in the world without many worries because nothing much else matters to be honest
I mean ... The world ends for those that die so from me , please, try not to worry much about it, relax, life will go on, with or without us, so enjoy your time. Call a friend or a relative and just chat a bit, drink some beers , have something to eat and smile.
Thats what I would do , it might work for you (or not) but at least I said my piece.
Cheers and big hugs!