I do keep a journal, though it is not very consistent, I'm sorry to say. I mostly write in it when my heart becomes too full that I need to spill it's contents onto paper... it's a mixture of a lot of things, day-to-day, heart struggles, my spiritual walk, relationships, etc.
Journals are a great way to see how one has grown over time. I would recommend doing so, even if you don't do every-day entries, it is encouraging to look back, and see from what you've come, in your better perspectives, attitude, and spiritual growth, because sometimes, well, a lot of the time, we don't see the change that takes place as we grow.

(ramblings)