Fear of living and not living at all. . . Although I have not read all the posts here with great care, it seems that some posters, at least, would find the idea of an eternal existence to be tiring and dreary at best, insufferable at worst. For my part, I can imagine being perfectly happy to "carry on" forever. However, I say this with a great deal of trepidation as I can imagine there would be some aspects of an eternal existence that are either not even imaginable or that I have not though carefully enough about.
Let's talk about ways we could imagine an eternal existence to be intolerable. My life, like all lives, is not entirely a bowl of cherries (however, on the whole, I am confident I have been more fortunate than most, but who knows?). I live in a very cold climate - what would it be like to face an eternity of Januarys? When I was in my 20s, I embraced the cold; in my 60s, I find it very unpleasant, and increasingly so. Perhaps after several thousand Januarys you would need to talk me off a ledge. On a more serious note, I, like almost everyone, have experience the loss of something dear to me (relationships, a job I loved). Could I tolerate an eternity of experiencing such loss even if such events were infrequent?
Likewise, would I tire of the good things in life? Perhaps the pleasure in eating an ice cream would be greatly impoverished were I to face an infinite number of cones to lick in the future.
In short, would I tire of existence? My guess is that I would not, but that is almost certainly because I expect that, were I to live forever, I would become increasingly resilient to the challenges of life and would therefore not be overwhelmed by them.