I was never good at keeping a journal.  Except for once when I was an exchange student in Grenoble, France my junior year of high school.  It was hard to force myself to sit down and write something every night, especially when I was doing all of these cool European things.  But now I like to look back on it because you can clearly see how my journal entries transitioned from English to French.  I remember that point where I began to think in another language.  I wish my French were better now.