Yeah. Such philosophical analysis bugs me too. I think any degree of "I can always do this tomorrow" would be more than offset with "I've got the time to do a bunch of things I might otherwise not". I think the day to day pleasures would be pretty much the same. While I suppose there can be some amount of jadedness with regard to "new things" as we get older, that still doesn't prevent me from enjoying watching a film, even if the plot is pretty standard stuff I've seen many times before. And going out to eat with friends is still enjoyable, even if you've done it a hundred times before (one can argue it maybe becomes more enjoyable).

I also think that maybe the kinds of things you would enjoy doing and therefore actively involve yourself in may change if you had forever to live, but I just don't buy the "no reason to get out of bed" bit.

And yeah, that's before examining that people might be even more interested in involving themselves in longer term projects, goals, whatever, if they know they'll live long enough to see the results (of either success or failure). I'm probably going to be a lot more interested in investing in, say space exploration if I know that maybe one day I'll be able to travel to other planets than if it's assumed that this "might be something future generations may do". Dunno. I could see a lot of things being different given a different perspective like that. But definitely don't see pure apathy being a likely outcome.

Not sure how this fits into the idea of an "eternal soul" from an afterlife in stick world though. I think the bigger problem with souls lasting "forever" would be that in that case, they are removed from the prime material plane, aren't really doing anything that impacts anything, and so yeah, I can totally see the concept that over time, you'll just sort of fade away into a generic version of yourself/alignment/whatever. But that's not a function of immortality so much as being in an environment where nothing you do actually matters.