I use Obsidian with a "daily-planning" template that has a bunch of typical journaling prompts. I customize it over time, adding new ideas and removing boring bits.

Current sections are: - Things to remember - List of 10 important quotes/mantras - What's on my mind - How am I feeling productivity/mood wise today - What do I most want to accomplish? - What would make today horrible? - Gratitude - Something Mundane, something that happened by chance, something I made happen