My husband and I are getting more accustomed to this aspect of our CSA subscription (community-supported agriculture, where we get regular food deliveries from a local farm): using what we have on hand. Every week, we get whatever is in season, whatever crop successfully made it to ripeness. And that dictates what's on our menu for the week. It's made us try all sorts of foods we wouldn't have otherwise. Because of the CSA, I've eaten kohlrabi, and salads with turnip, and chard omelets, and salmon with fennel, and zucchini bread, and rhubarb cobbler, and spaghetti squash, and a host of other foods.
The other day, we got a lot of peppers, so we had chili. And it's this "what can I do with what I have" approach that's different from how I cooked for most of my life. For most of human history, people had to eat whatever was available, but nowadays, in my location and at my income level, it's possible to go to the store and get almost any food I want--whether or not it's in season, whether or not it grows anywhere near me. It's a luxury, one I used to take for granted but don't anymore.
The writing connection (you knew I'd get to the writing connection eventually!) is that there, too, it took me a while to get the concept of using what I have. For a while I tried to write like writers I admired but whose voices and subject matter were very different from mine. I tried to write what would be easier to sell. I tried to write what seemed like good stories--but turned out to be good stories for someone else to tell. And eventually I started using what I had. I started basing my writing on what I had to say, and on my own voice--which proved to be a much more natural wellspring.