In the past few hours, you have probably experienced a few moments of somewhat dimmed consciousness. It's perfectly normal because the energy levels in our brains do fluctuate. Now, it's not really all that hard to think about the concept of not being alive anymore at all. The fact of the matter is that it's simply a total blackout of your awareness. It's nothing exciting or remarkable. It's simply an erasure.
The fact of the matter, though, is that we worry about it because we don't like the idea of being rendered ineffective. We try our best to avoid it because, once you are permanently incapacitated, it's done. It's not very dignifying, really. That's why, in our elder years, we go to so much trouble and expense to try to insure that our "final arrangements" are being seen to, making sure that our survivors are taken care of and getting our estates in order. There is little we can do about our mortality, but we can do something to hedge against being rendered thoroughly helpless. We can leave our business to a responsible son or grandson. Sure, in our waning years, we might worry about its future, but we have done the best that we can.
Ultimately, people worry far too much about death. You can have a long life. Make it a productive one. That will make others around you happy with you. You can do a very good job. You can do a sufficient job. You can be enough without having to be around forever. We won't judge you harshly or say nasty things when you are no longer able to defend yourself. After you have spent yourself as well as you can, we promise to do our best to continue taking care of things, and you will be held in good esteem. Erase your worries.