In addition to what @User said about having workable goals—I think of these goals almost as a way to "filter" my interests—you might reconsider what you're doing with each note? For instance, you might consider archiving any mostly empty ones into a "someday" vault? I have a lot of notes with links to websites or books that I'd like to read, if that interest becomes more truly "useful." It's sort of a "someday / maybe" list, like GTD recommends, as well as a way for me to document what I've been interested in, in case I'd like to pick those interests up again later. It's not as satisfying as having infinite time & resources, of course, but it does at least let me feel like whatever inertia / progress I've made on learning a new topic won't just disappear.