One way to encourage yourself when setting out to keep an art journal is to have an easily accessible set of supplies.
I often find myself with time to work on a page only to arrive at an art table buried deep in stacks of magazines, or piles of pens or the remains of the last kid day. OR if the art table is cleared (miracles of miracles) and I get to work on my art journal, I spend half the time trying to locate a specific paint, or picture or rubber stamp. I have reorganized any number of times and still find that I am not organized.
Just recently I came across a brilliant book by
1. Everyday Supply Kit
3. Travel Supply
In the book she lists what she keeps in her kits, and these lists can be easily modified for your own needs. She is so efficient that this system seems to work whether you have a large studio or if you work on the kitchen counter after the kids are in bed.
In the same section of the book she also clearly tells you how to set up a workstation. The idea is that when you walk up to your art table or when you have a moment to work on an altered journal, the supplies are waiting right there all in one place for your use and your valuable time is spent creating, not searching.