Creating a masterpiece of modern literature consists of two completely different steps: writing and editing.
(Note: The process of actually getting said masterpiece into the hands of the masses consists of many more additional steps, which I'll not treat here. I digress.)
These two operations—writing fiction and editing fiction—are wholly different from each other. They require different skill sets to do well, and they require / evoke different moods in me, the author.
(Note again: I've taken to calling myself an "author," as distinct from a "writer." That's because I'm a "writer / editor," and "author" is a shorthand way of expressing that. But I digress again.)
It seems easier to edit than to write. Editing can be done in little bite-sized snippets, re-reading a scene or two and "tightening up" the prose, checking continuity, adding beats, making the text generally "sing." On the other hand, writing new text requires a commitment. I must get myself into the proper frame of mind, think about where the story should go, put on the mantles of each of the characters and consider where they want to move the action. I often spend more writing time staring into space, thinking, considering, than actually typing.
(Sorry, note a third time: I was going to say "chewing on my pencil," but I don't generally use a pencil, and "chewing on the keyboard" just sounds desperate. Right, back to the point.)
Writing is like building a bookcase, and editing is like sanding and staining it. Walk into an empty workshop, no plans in hand, and start putting together a piece of furniture. This takes some thought, some work, some time, and a creative mood. Walk into a workshop with a constructed but unfinished bookcase standing at its center, and it's easy to pick up the sandpaper and start removing the imperfections, without very much consideration. Sanding is easy to do piecemeal; building is best when done at one go.
I find it entirely too easy to fall into the trap of editing and re-editing what I've written. It needs to be done, but not to the exclusion of adding new prose—of actually finishing a novel. To do that, I'm going to have to start setting aside specific periods in my day to write, as I did during last year's NaNoWriMo, so I can take the time I need to get myself into the writing mood. I keep telling myself this, but I haven't done it yet. Here's hoping I can start this week. It's never too late to re-ingrain a good habit.
(Note a final time [to self]: I really need to go back and edit this entry. It needs tightening up; there are too many distracting asides. Hmmm. Maybe I'll just go write some prose instead...)