There are a few different phases an author goes through when writing something. Whether it is an assignment set by your teacher, a story you are creating, or an article for your job: you will always reach these phases.
1. Motivation
When you first decide to write, you obviously can not start until you have an idea you write about. This phase is often times a difficult phase and turns many people away from writing. However, if you can stick through this phase, your idea could spark the interest of writing for someone else.
2. Excitement
When you do finally decide on one of your many ideas to write about, you could not be more excited and more devoted to this one idea. Your thoughts about it come flying out at 100 miles per hour and none of them are sticking to the paper. When you do manage to get something down, you think of a better idea five seconds later and replace what you already had. Sometimes you replace what you had four or five times.
3. Discouragement
At this point you have gotten a chunk of your paper done, and you are starting to slow down with your ideas. You end up rereading what you have written down in front of you and you can not help but think about how stupid it is. You do not think anyone will read it and have the same excitement you had when writing it. More papers die at this point than survive.
4. Feeling Content
This is the phase where you finish the paper. You read it and think that there are several things you would like to change, but you can't. You know that if you change one thing, another thing will bug you and by the end it will be a completely different story. You then feel content with it and turn it in.
As a writer, I can attest to the fact that some of the time you will find more things wrong with your paper than you don't. You may even think that your paper is complete trash and a waste of time. Just remember, one man's trash is another man's treasure.