Marjorie Lui, who attended LaunchPad with me in July 2010, recently wrote at http://marjoriemliu.com/index.php?/blog/comments/rambling_about_dragons_and_passion/ about maintaining your passion while writing. If you remain interested, she contended, so will your readers.
I liken writing to running and, for myself, I find it easier to maintain a high state of excitement and interest in either only for brief periods. In one sense I am a sprinter, focusing on the goal at the end of the course and not very interested in on the path. Just like you cannot sprint carrying too much weight, a short story's interest cannot be maintained if it carries too many words/characters/scenes/events. In both cases, one must cast off the unnecessary, avoid distractions, and race for the end as fast as possible.
Novels, on the other hand, are like marathons. One can start with great enthusiasm down the path with a clear sight of the route ahead but somewhere along the way interest starts to flag and, at the halfway point, it becomes a matter of putting down one word after another and wondering if you have enough of that initial enthusiasm left to keep going.
As in marathons a wall awaits. Somewhere along about seventy thousand you find yourself drained of ideas, enthusiasm, and even words. The ending is still a long way ahead and you suddenly realize that you have only a vague idea of how to get there. Continuing beyond this point feels like you are piling one lifeless word, one limp sentence, one appallingly bad paragraph on top of another, adding to the tragedy of pages you have steadily accumulated over weeks, months, and years. Is there any sense in continuing this farce, you ask yourself as you continue. Eventually, if you have not totally abandoned all hope and maybe after a break to refresh the old story-telling muscle, you return to the race and, when you are in sight of the goal line, sprint like hell so you can tell yourself that you are - unbelievably and astoundingly - finished!
And then a little bitty bitchy voice comes from no where and tells you that the finish is an illusion. "Back to the starting line," it demands and you find yourself retracing your entire run, step by step, word by word, exploring all the little byways and digressions, continually asking if it was necessary to the rambling plot, should I have gone this way or that, why did he change his name here and who is this character that appears to be so interesting only to disappear without explanation. Question after question, you climb over enormous, numbing blocks of text that seemed so golden when written but now make no sense. You move entire scenes from one place to another and then, just when you've finish the course for the second time, you realize that you have to do it ALL OVER AGAIN!
It takes far more than interest and passion to finish a novel. It takes grit, perseverance, and dedication. Enthusiasm alone cannot sustain you.