What’s in the world around you? Do you at times cringe at what you see? Do you take pleasure in what beauty befalls your eyes at various times? Or do you turn your back on it and say “BAH”? Well, I say there should be a happy medium of both good and bad and then make it what you will.
When we as adults are learning something (whatever it may be), be bring to this new knowledge our prior experiences so as to make comparisons. In turn this brings understanding. Plus, we can use the prior experiences of others to learn from as well. What you are doing here is building your knowledge, increasing it even, so you can draw upon it later and use it.
In creating a fictional world, we are doing essentially the same thing. We draw upon what we know of our everyday world around us and places we’ve traveled to and fictionalize them, or we use bits and pieces of it and create a world of fantasy and magic.
Use what you see. Take notes of it. Brainstorm ways you can use it. Draw a map of your created world. But don’t stop there. There is more to world building than its looks/appearance. Made up world have their own government, gods, religion, beings, environment, etc. Below are some links to some great books on world building.