When creating your PBOK know the major themes in your life. Your themes will be the topics that you will organize your information around.
Themes could be the different areas of your work, your pastimes, the roles your play, and the different things you are learning. The key is to get the structure in place to attach your reflections and experiences.
With the structure in place, your reflections can be found in the future.
As you journal you will identify more themes which will lead you to refine your notes to connect them to the new themes.
Eventually, your PBOK becomes a web of information that is directly relevant to you.