Here is one of the reasons journaling is so powerful.

Whenever we do something that makes us feel good or bad, it helps writing down what happened and what we observe, what we think the reason is.
Over time, we will find more and more things that feel good or improve our life, poker and health and find also the inverse, the things that make us feel bad, rob us of energy and simply drain us.

The more of these things we find, the easier it becomes, doing more of the things that make us feel good and just as importantly, if not more, do less and less of the things that drain us.

If you for example don't enjoy really tough workouts, however, if you do a workout that is say 10 minutes in length and is only something like 65% of what you can do, it might help you feel great, because you get your body going, your muscles are activated and overall, the bloodflow in your body increases, releasing some endorphines (happy hormones).

Yes, true, this workout might not improve your overall strength and fitness by a lot, but it will boost your life and make it so much easier to get into the habit of training regularly, because, you are after all doing something that is not very hard, but makes you feel amazing asap.

This is another little key here, getting instant gratification, because of the increased bloodflow and the release of the hormones, while your brain does not associate it with "annoying" long workouts, but with nice bursts that make you feel awesome.

Whenever you can, write down what works for you and what does not work.
Upon doing so, you will also increase your awareness of the same and in time you will be able to listen more accurately to yourself and what your mind, body and soul are communicating to you, you will hear it and you will more and more often also understand it !

The same goes for your poker, keep notes on yourself, not just on opponents. What plays worked, what plays did not, were there influencing factors that let you to block out one or another thought that you only realized afterwards you should have had?

You can keep different journals and don't worry about making super long posts and have that keep you from doing it. The entries can be very brief, you can even play around with structures, or shortcuts of how you want to take notes. Experiment with it, Trial and Error, and Adjust.

Enjoy, have fun with it.
Get great at observing nature and yourself !