After many days, weeks, even months, you’ve finally reached the end of your story. You have a first draft.
Congratulations! Your work is just beginning.
If writing is like archaeology, then finishing your first draft is the physical labor of digging up an ancient site. You find a site to dig at (get an idea), hire the best people to crew the dig (figure out your characters), and spend months breaking your back and scrabbling in the dirt trying to uncover an Egyptian tomb or Norse burial mound without breaking it any worse than several thousands years already have (write, damnit!). It’s rewarding work, and every now and then you find a coin, or idol, or cursed amulet that turns three of your crew into werewolves before you manage to slay them with an ancient sword, setting you on the path to becoming the one immortal ruler of…
Sorry, got a little carried away with my metaphor there.
The point is that actually writing your story is hard work, but it’s the part that can be explained easily. An archaeological expedition digs (carefully, following specialized protocol) until they run out of time and/or funds, then they haul everything back to whatever research facilities they have and begin the tedious process of interpreting all of the pieces to form a historical narrative. If all the National Geographics I read as a child are to be believed, that time spent researching and interpreting is what actually comprises the majority of an archaeologist’s career. Likewise, a writer spews ideas on to the page over a given period of time, then has to set about the arduous process of turning those ideas into an actual story.
And that can take some time.
Now, there are some writers out there who will say that they can churn out a novel in a few weeks (or days?), spend maybe a week cleaning it up, and call it done. To them I say a hearty, “Congratulations!”
It is possible to produce high quality work at a rapid pace. Just Google “written in a week” and weep as you read list after list of great works of literary genius literally penned by writers at a prodigious pace. Burgess. Faulkner. Fleming. Who wouldn’t want their name added to the litany of literary greatness, and in only two months? Whenever I think about fast writing, I imagine Crime and Star Wars firebrand Chick Wendig hunched over an animatrix-esque mechanical keyboard, pounding down whiskey as he pounds out whole novels in days. How accurate this image is, I do not know. Hell, L. Ron Hubbard was rumored to clatter out over 300 pages of scientifically inspired truth every alien-damned month, and still have time to bed Robert Heinlein’s wife, drink heavily, and found a religion. And I hear that Alexander Hamilton wrote 51 essays defending the Constitution in only six months.