The act of writing your feelings helps you interpret and make sense of your own emotions and personal feelings. It can help improve your mood by helping prioritize physical and emotional problems, fears, and concerns. It can help provide an opportunity for positive self-talk. Writing your feelings down can help you identify negative thoughts within your mind. This can happen in many different forms from journaling, writing short stories, or poetry. 

Personally, when I go through tough times the act of journaling and writing poetry helps me organize my inner thoughts and think more clearly.