One realization I've had is that, for all of the projects that I started and never finished, or even never started, I would much rather have that project finish

One realization I've had is that, for all of the projects that I started and never finished, or even never started, I would much rather have that project finished and done and part of my project portfolio, even if it really was a dumb idea, than to have given up on it. If I can really truly believe that and act on it, then it makes since to follow through and finish projects, regardless of if after a week I think it's a dumb idea. Now, of course, some ideas may really be dumb. You have to have some mechanism for filtering out garbage. I propose filtering at the beginning: make at least an informal design of the project, and if, after that, it still seems reasonable, then commit to yourself to finish it. And finish it before starting another personal project.