I like the idea of this sub so I thought I'd contribute the first post.
I'm 40, and I have cancer. I don't know if I'll survive or not. Being in this position though has forced me to get all my "life stuff" in order, and boy, I can tell you there's a lot more of it than you realise.
Start now. Especially if you're healthy, double especially if you have a spouse and/or kids.
I get it that nobody wants to think about their own mortality, but consider that what you're actually doing is making things easier for your family.
Get a properly done will from a lawyer. Not one of those "write your own will" kits. It's not just about who gets what, but also burial vs cremation, who will be your executor, any special gifts/request, who is next in line if your beneficiary dies etc.
Organ donation? Tell your relatives AND register.
Insurance. Get life insurance as its the only insurance with a guaranteed payment BUT calculate yearly cost vs how much you would have if you just put that money in the bank. Amount should cover all outstanding debts. Get separate insurance for house and vehicles.
Superannuation (retirement savings). Where I'm from they need a form filled out that tells them who your executor will be. If they don't have this, your executor will have to go to court and it's a real pain in the arse.
Photos. Get them off your phone and back them up using the 3, 2, 1 backup rule. Make sure someone else has access if you pass away. Photos are one of those things that doesn't seem important until someone dies and that's all you have left of them.
Power of attorney. Who will make financial and health decisions for you if you're in a coma?
Advanced health directive. If you're in a coma, do you want someone to pull the plug, or keep you alive no matter what? Read about Terry Schiavo to see why this is so important. Again, tell your relatives AND fill out the documents.
Consider prepaying for your funeral. Especially if your family doesn't have a lot of money. They're more expensive than you think. It may take weeks or months before your relatives can access your savings or insurance money, and they'll still have to pay for it in the meantime.
Hot tip: caskets are a waste of money; get the cheapest you can. I am friends with a mortician, and he tells me that most of them are cheap crap made in China with 1000% price markups. They get away with it because frankly, nobody's going to bring one back for a refund.
Write letters to the people you care about. If you die suddenly, they'll have a heartfelt letter as your last words to them instead of a text saying "Do we need more cheese?"
Relax. We all die eventually, but at least now you know that everything is taken care of. Your friends and family will still be sad, but at least your death won't be any harder on them them it has to be.
There is a book called "The gentle art of swedish death cleaning".
It's kind of like the whole Marie Kondo Tidying thing but with a different perspective.
The idea is that when you die, someone has to deal with all your crap. Dealing with all of your extra pointless crap while you are alive will improve your life in the present, allow you to enjoy the things you care about, and make it a lot easier for those who need to take care of your stuff when you are gone.
There was also a show on peacock, about it. Torrents are your friend.