I, like Roz, have kept a journal for a long time. I have taught journaling to adults, teens, kids - all kinds of journals. To me it isn't so much a daily habit, as suggested by a Unitarian whom she gave a talk to, rather a committed act to myself. Something just for me.
There aren't many things in life that are like that. When I cook, it is for others. When I drive, it is often for others. When I am working, well that is certainly for others. Even when I dress I am often thinking of others when I dive into my closet.
But keeping a journal, even sporadically, is just for me. No one reads them or looks at the sketches. There are no reviews or deadlines. I am not even doing it for posterity. I don't really care if anyone ever reads them. I don't think, out of context, that they would make much sense to others.
When I boil down why I do it, why I continue to scribble across the page it is because I am allowing myself that time. The time to hammer out an idea, dream a little bigger, whine - and it is all just for me. Just thinking about that makes me smile.