I have used journalling in different ways for many years to reduce my stress, save memories, assist in self-talk, or just save ideas for future writing projects.
Long before I had a computer, I used composition books; you remember the ones with the black and white hard cover. I still have a few of these that I use as reference material.
Computer documents make journalling fun and easy, yes fun because you can use different fonts and text colors to make your journal creatively you!
By removing this content from your thoughts, you cleared space for other thoughts, thoughts that can solve a problem or remind you to relax and enjoy just being. The concern that you will forget something important is resolved, the only thing you need to do is to have a catchy title to recall the entry.
Several different journals are great for the topic you wish to address. Always have creative titles for your journals and the content will flow better went you go to enter your comments.