I came across this wonderful article in the Paris Review where Joyce Carol Oates talks about journaling. As an avid journal keeper, and a writer, I found it fascinating. I hope you will too.
I began keeping a formal journal several years ago. It resembles a sort of ongoing letter to myself, mainly about literary matters. What interests me in the process of my own experience is the wide range of my feelings. For instance, after I finish a novel I tend to think of the experience of having written it as being largely pleasant and challenging. But in fact (for I keep careful records) the experience is various: I do suffer temporary bouts of frustration and inertia and depression. There are pages in recent novels that I’ve rewritten as many as seventeen times, and a story, “The Widows,” which I revised both before and after publication in The Hudson Review,and then revised slightly again before I included it in my next collection of stories—a fastidiousness that could go on into infinity.
Afterward, however, I simply forget. My feelings crystallize (or are mythologized) into something much less complex. All of us who keep journals do so for different reasons, I suppose, but we must have in common a fascination with the surprising patterns that emerge over the years—a sort of arabesque in which certain elements appear and reappear, like the designs in a well-wrought novel. The voice of my journal is very much like the one I find myself using in these replies to you: the voice in which I think or meditate when I’m not writing fiction.