There is a component of creativity that comes out of nowhere. At no particular time and for no particular reason, you might be struck by an image or a scenario or a dilemma that enthralls you. Maybe this happens to you constantly, maybe it's rare, but either way, that spark of inspiration can become the thing you're excited to write about (or express in the creative format of your choice). A creative project has to start from something, and this so-called visit from the muse might be the best source for an idea you actually care about.
But any creative project requires a whole lot of ideas, not just a starting point. That sentence you overheard can inspire your novel, but you're going to have to make a million decisions about character and plot and setting to transform that sentence into a story, and that's leaving aside the fact that you also have to sit down and write the damn thing. Since so many brilliant ideas come unexpectedly, it can be tempting to wait around for as long as it takes for all the right pieces to fall into place in your head, but this isn't generally the best tactic.
Coming to every decision in its own sweet time could take forever, so it's important to apply the same discipline to planning and thinking as to writing: Show up and do the work whether you want to or not, whether you feel inspired or not. This won't be effective absolutely every time, but usually, all that's required to get things flowing is to make a start. Focus on the problem, stare pointedly at research materials that might lead to ideas, and a solution will become apparent. It's not magic, it's persistence.
Once you've had a little success with the just-do-it strategy, it can again be tempting to sit back and let the rest of puzzle assemble itself through those useful flashes of brilliance. This might work, after all, now that you've solved that one big problem that was plaguing you for ages.
Don't do that. A crucial aspect of persistence is that it's ongoing. To really accomplish anything creative, you have to work at it and work at it and work some more. Even if it's summer and there are new books out and vacations to plan.
This post is of course simply a timeless observation, relevant to nothing at all particular or currently relevant.
Good Stuff Out There:
→ At The Millions, Jonathan Russell Clark examines The Art of the Epigraph: "Writers don't use them to boast. They are less like some wine and entrée pairing and more like the first lesson in a long class. Writers must teach a reader how to read their book. "