I have found that one of the hardest things to do is to fill up a journal completely. I fall too easily in love with a new one before even finishing an old one. My entire life is going to be documented in half-filled journals scattered from Houston to San Marcos to wherever. They're one of my favorite things, journals.
I've always wanted to buy a journal or a sketchbook and have it be passed on from person to person. Each person could probably keep it for a week or so, and when it's filled up the last person would mail it back to me (somehow these instructions would be incorporated visibly into the journal). I don't know, thought it would be pretty interesting!