Another way to approach a problem is to ask a question by writing it with your dominant hand and then answering with the other hand. Look at what you've written. Unlike the diary of the past, where you dutifully recorded the events of the day, your journal's purpose is to capture emotions between each moment. The absolute most important advice I was ever given was to let my writing materials choose me, rather than the other way around. I use a spiral notebook.
Some people prefer legal pads or loose-leaf binders.
When you shop for supplies, feel the paper and note whether it calls to you. Hold the pen or pencil in your hand. Sample both on in-store displays. The Place Experiment. A table near a window with a view of the sky or trees may be what you need.