Mindfulness journaling is a great way to get in touch with your thoughts and emotions. Journaling can increase gratitude, increase optimism, and decrease stress. One study even found an association with improvement in working memory! Even a few minutes of mindfulness journaling daily can change how you feel about yourself and your life.
And remember that this writing is for you! It doesn’t have to be perfect or eloquent. Let yourself go on rants or tangents if you feel the urge to. Don’t suppress anything. The act of writing your thoughts is more important than the outcome.
You could start journaling in any notebook, but there are also specialized journals for those that need more of a guided approach. Having a structured notebook (specifically for mindfulness journaling) is an excellent option for beginners, as it helps you stay on track. Amazon has some great options, including this one!