Writing is an interesting exercise in creativity, since you have to craft ideas, stories, and even sentences, but also an exercise in production, because whatever way you look at it, you are attempting to work. In this sense I could almost say that I have a part-time job. Unfortunately, it doesn't work like that. Regardless of what you call it, writing is a lot of work. You have to constantly think about what you are writing but also you have to be constantly aware of what you did write and what you will write.
You could probably ask any writer and they would tell you that writing is grueling process full of frustration, confusion, and large doses of caffeine. It doesn't matter whether you are writing a paper for a class, a proposal for work, an article in a newspaper, lyrics for a new song, the code for a program, the first draft of a novel, or even a blog entry. It takes a long time to complete a work you are fully satisfied with. And I'm speaking from experience here.
Of course, your input normally directly effects your output. I'm finding it hard to believe this to be true, however. I have been going through this process hardcore for the last couple of months, since I am writing a book. On many occasions I have put in an immense amount of time but gotten very little actual writing done. I guess, however, that this can be said about many creative endeavors.
There are always thoughts about what might or might not happen, thoughts about whether this will succeed or fail. If you get too caught up in those thoughts, then you end up spending more time distracting yourself with make-believe situations than you do actually writing your story. This has happened to me a few times. The problem is, you only really realize that it happened after the fact.
All this discussion isn't even getting into all the issues, outside out time and effort, that involve crafting a story. You need a believable plot line, rich and interesting locations and characters, and well chosen dialogue. There are also other issues that you must consider such as, "What is the point of this story?", "What sort of message do I hope to convey?", and "What do I want the reader to feel about this or that?". Those are all issues that an author needs to address and I'm trying to hit them when I get to them.