Journaling is a very simple thing to do — in term of what it literally is. It's just writing about your emotions, mood, goals, what you've learned, etc. But you gain sooo much from it. Like many others, I've gained from journaling in a way I didn't expect... So it's hard to reduce journaling to "just journaling". It's a practice, similar to meditating. There is no cap to the benefits you can get from journaling.