Writing is hard work for almost everyone, no matter how talented or inspired. Writing is thinking. Good writers do not usually have finished ideas that they then type out. The process of writing and revision is an act of thinking and discovery. That is why writing papers can be so frustrating and rewarding at the same time. Want to improve your prose? Keep a journal, in which you produce a page of text per day. The text can be about anything, but use standard prose, not the kind of abbreviations and lack of capitalization that you might use in informal emails or IMs with friends. The text should also be honest. This exercise is akin to doing regular physical exercise, practicing music, or learning a foreign language. The more you do it, the better you get. The less you do it, the worse you get.
I wrote the above piece for my students and posted it on a course blog called History Survey. It then migrated to Language for You, before settling here.