I think authors of predominantly short stories and short-shorts find writing a much more enjoyable thing. They can come to an end of a story in about a week or two, and then they can edit, and be done with it. This isn't to say that what they do is easy, because it is not, but I think authors who venture into the territory of novel-writing are intrinsically masochistic. Writing a novel will undoubtedly test your mental fortitude, and make you -- more than once -- have rather funereal existential breakdowns where you are your own worst enemy. Think you're up for it?
This will become your imagination's calling card every day as you sit down to write.
"I'm so bad at this."
"This is never going to get published."
This will follow you when you save your document for the night.
"All of my characters are thinly veiled interpretations of myself."This will haunt you as you read it over with a critical eye.
"I didn't write anything AGAIN today."This will become your own, personal cat-o-nine-tails that you flagellate across your own metaphysical back.
It is truly, as Colum McCann says in LET THE GREAT WORLD SPIN, "another day, another dolor."
And despite all these things, you have to, as Ms. Gardner says, love what you do. It's not ALWAYS fun (though I do find that most of the time it is), it's not ALWAYS an eye-opening experience (though there are definitely times...), and it's certainly not always artistic. A novelist is slave to the details. If you want a character to move around, you must get him there, one way or another. Bus, train, car, missle, rocket, submarine, alien transport, or sky bridge made out of crystal.
Novels are, ultimately, labors of love. You must love them, but there is no guarantee that they will love you back.
But you're okay with that, right?