I was a funeral director. I talked to a lot of people about death and I can't recall a single old person who wasn't alright with dying.
The way some have explained it to me was basically the novelty of life was gone. When you're young, everything you do is new. You experience things for the first time daily. As you get older, new experiences are far and few in between. Every day becomes a copy of the day before. Weeks pass where it seems nothing has happened, but its only that nothing new has happened. Old people eventually just get bored. Combine that with chronic pain, being unable to do basic things on your own anymore, and all your friends dying before you, and the idea of not waking up tomorrow doesn't seem that bad.
This. We all love life. It's a gift we didn't ask for that we should cherish and make better for the next generations. But it isn't all positive moments. Bad things happen to good people and good things happen to bad. Slowly chipping, away exhausting your mind as your body breaks down in new ways you didn't think of or know possible.
You don't give up the fight because your alive and it's against human nature. But removed we are tired. A long nap seems peaceful. I wasn't incovenienced before I was born life keeps churning. I'm thinking it'll be the same after I'm gone. It's not from a place of insignificance. Rather you relish the good and positive you've done in life. You come to terms with it.
Of course, when you're young you don't think about it, then comes the time that your grandparents pass, or a pet, and you get to experience a form of grief. As time goes by, you start losing more people you knew, a school friend, a work colleague, an aunt... And eventually death comes closer and takes away your parents, your social circle shrinks, you think of your own mortality.
Then you eventually think what will happen when you disappear. What if it was tomorrow, when crossing the street? What will people you leave behind remember of you? How can they deal with your stuff? Can you make it easier by lessening the amount of stuff you hoarded? Can you put down the important information to your online accounts somewhere? Will they be able to let the friends you made over the internet know that you're gone?
Statistically, I lived half my life, and those thoughts come and go. I look at stuff in my cupboards that i haven't touched in years and decide what to do with them. I start making preparations for the legacy of my many accounts for social media, banking, internet hosting, image backups etc. We're all here on borrowed time.
Das letzte Hemd hat keine Taschen.
German saying: the last shirt has no pockets.
What you wear on your last day on this Earth doesn't need pockets because everything stays behind after you die.
I used to think about it a lot when I was younger because it seemed so unfair that life comes to an end. As I've gotten older (and closer to the inevitable) I think about it less. Hopefully you'll get to the point you realise worrying about something you can't change isn't productive use of the time you have left. That doesn't mean you shouldn't do what you can to eat well, keep fit and put off that final reckoning as much as you can.
Middle age guy here (if I live out my family's typical life expectancy).
I try not to worry about death, as it's something I can't change. Doesn't mean I'm ready for it to happen tomorrow, just that I realize that it's going to happen when it happens and isn't worth wasting thought on outside of preparing affairs for it once it gets closer.
I'm not religious, but I've had an experience (and others have had experiences, such as out-of-body NDEs where the details that they witnessed in places and circumstances they shouldn't have been able to see were later verified by others) that indicate to me that we continue on somehow after death... it's not a nihilistic void.
But even if it were one... that's not so bad. You wouldn't perceive stimuli, you wouldn't notice time passing... the unbelievably long mass of practically eternal time between your death and the death of this universe would be the blink of an eye for you. And if scientific theories about Poincare recurrence of the universe are correct, then eventually you'll go trhough life again from the same starting point, none the wiser that you didn't exist for an unfathomably long time.
In short, try not to worry about it. You can't change it, and once you get there, there's either something or absolutely nothing afterward... and you'll be fine either way.
Edit: spelling
Yes, as it gets closer I feel different about it. I'm still having a good time being alive, but all my kids have made it to at least legal adulthood, so I don't have to worry as much about what would happen to them, and I've had a reasonably good life in terms of an arc from abject poverty to a solid middle class (like, the disappearing middle class sort of middle class) existence, have seen so much good live music, read so many good stories, solved problems, learned skills, helped some people, it's been a good run & I would be satisfied with my life even if I had to die now, if that makes sense. I don't want to yet but it's less of a worry than it was.
I have thought about it in terms of a young death and tragedy and the whole. They never got a chance to live. So my feeling is once your in your 50's you can't be said to have not had your shot. Your not super likely to die but if you die its just a thing at that point.
