Personally, these days I tend to lean into that feeling and use it to help guide my decisions rather than try to fight against it. I've already been through the ringer, so to speak, where I spent 10 years chipping away at a story I conceived in middle school only for it not to go anywhere or amount to anything. Now when considering new projects or story ideas, i try to listen to my gut. If it says "hey, whoa whoa whoa! That's really long, do you think you'll actually be able to finish that?" I take a moment to think about it and if the answer is realistically "no" I put it back on the mental shelf and search for something else. It doesn't mean that the idea will never be worth it, but I'm just not in a position to take on any like 5 year+ projects right now lol.
Big agree with the above comment though. I definitely believe in a "nothing ventured, nothing gained" approach to creating~ Part of how I know to trust my gut in the present is because of the projects that I've done in the past- both the ones that worked out and I finished, as well as those I didn't.
For example, I'll talk briefly about my most recent project which I just finally abandoned a few weeks ago
I had been working on it for a year, since last June, and had just slowly been losing the drive to work on it over time. I limped it along for several months past its "prime" before finally throwing in the towel. But I got so so so much out of the experience of making it too! It was my first time experimenting with vertical scroll, and I practiced anatomy, perspective, and paneling a lot, and I tried a new type of upload schedule, and a slightly different genre than I had ever worked with before, and it served as my introduction to art streaming, and the specific reasons why it didn't work out in the end now have been added to my gut sense for "think twice about doing something like this again". So even though it was a "failed project", I still had a blast creating it and now when looking for whatever comes next, I have more points of data for "do"s and "do not"s~