"All you have to do is write one true sentence. Write the truest sentence you know." That's what Hemingway said and I love him for that. To write the truest sentence I know is to focus as a laser focuses. When a laser focuses it fixates on one thing only. To write then, for me, is not to merely look at a picture and describe what I see. It is to concentrate on one element of that picture with acute precision and describe what that element is doing frame by frame.
To write truly, one must be able to hunker down as if on one's knees, bar all distraction, and locate one grain of sand on a beach and describe with pinpoint accuracy its character while not confusing it with its infinite adjoining ranks.
To write truly, one must slow down, knowing no hurry. For true life never hurries. In not hurrying one may catch the ups and the downs, the time and the space, the colors and the textures, the obvious and the obscure, being free to secure them, as it were, one true sentence at a time. This is writing at its best.