The end will come. I know, it’s not the most cheery thought to start with, but it is an ultimate truth. There is not, has never been and never will be someone born who will not die. . . physically. (Ok, there are a few exceptions, ie. Jesus, Elijah, and Enoch) It is an odd circumstance of humanity that while, yes, our physical bodies will die, our souls are immortal. They have no end.
That truth can be the most significant source of peace in our lives or the most significant source of anxiety.