I used to struggle with this, but came to this viewpoint:
Giving yourself permission to stop working on something you're not interested in is the other side of the coin of giving yourself permission to start working on something you are interested in.
I now think it's fine to just not finish things. You're more likely to do something you really care about if you stop doing all the things you don't care about.
OP kind of lamented projects that they gave up on after just one sitting ("on the rare case that I even managed to continue work on a project past one session"). But the opposite of giving up on a project after one sitting isn't "magically completing the project", it's more like "sitting around and watching TV instead".
- Working with rather than against things. Large problems are best solved by subdividing them into small problems. And in maintaining a constant light pressure over time rather than short-term extreme exertion.
- Seeing activities as serving some purpose. Whether that's writing or reading, undertake the project or book if it serves a need, take it as far as necessary for that purpose, and don't consider the task itself to impose an obligation, that comes from the goal, not the methods or journey.
- Having a set of drafts or sketches, or even just a conceptual structure or framework to apply to questions or problems, is highly useful. A Mastodon contact wrote recently of being asked to do a livestreamed presentation with no prior warning. There are a few possible responses (a hard "no", or converting the session to a Q&A or panel, say), but one option is to have a set of not-entirely-completed drafts which might be pulled out and deployed in such cases.
(I suspect that this is the basis for a large number of invited or commissioned works in literature, music, drama, etc. Have a set of pieces which can be rapidly assembled to create a serviceable whole.)
...and actually "finishing" that project only serves a subset of those. It's important to keep your motivations in mind rather than adopting a "must ship or I've failed" mentality. In particular, learning and SOFA go hand-in-hand
Giving yourself permission to stop working on something you're not interested in is the other side of the coin of giving yourself permission to start working on something you are interested in.
I now think it's fine to just not finish things. You're more likely to do something you really care about if you stop doing all the things you don't care about.
OP kind of lamented projects that they gave up on after just one sitting ("on the rare case that I even managed to continue work on a project past one session"). But the opposite of giving up on a project after one sitting isn't "magically completing the project", it's more like "sitting around and watching TV instead".