I am essentially imagining you to be similar to me about five years ago.
It sounds like you are not really excited about anything in your own life. You're probably more excited about far-future hypotheticals than about any project or prospect in your own immediate future. This is a problem because you are a primate who is psychologically deeply predisposed to be engaged with your environment and with other primates.
I used to have similar problems of motivation and engagement with reality. At some point I just sort of became exhausted with it all and started working on "insignificant" projects like writing a book, working on an app, and raising kids. It turns out that focusing on things that are fun and engaging to work on is better for my mental health than worrying about how badly I'm failing to live up to my imagined ideal of a perfectly rational agent living in a Big World.
If I find that I'm having to argue with myself that something is useful and I should do it, then I'm fighting my brain's deeply ingrained and fairly accurate Bullshit Detector Module. If I actually believe that a task is useful in the beliefs-as-constraints-for-anticipated-experience sense of "believe", then I'll just do it and not have any internal dialogue at all.
The part about not being excited about anything sounds very accurate and is certainly a part of the problem. I've also tried just taking up projects and focusing on them, but I should probably try harder as well.
However, a big part of the problem is that it's not just that those things feel insignificant; it's also that I have a vague feeling that I'm sort of putting my own well-being in jeopardy by doing that. As I said, I'm very confused about things like life, death and existence, on a personal level. How do I focus on mundane things when I'm confused a...
If it's worth saying, but not worth its own post, then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should start on Monday, and end on Sunday.
4. Unflag the two options "Notify me of new top level comments on this article" and "