It was always for me a form of therapy and now it also became a hobby. Whenever I was in a bad mood, putting my feelings and emotions down on paper was helping a lot. Along with words and tears my mood was getting better and I could close the past behind.
Writing has been therapy at times. It's always helped me to get things down on paper and out of my head even if they were shortly thereafter shredded and thrown away. Sometimes it's better to write it and no one see it but me and get it out of my system.
When I'm unhappy, I don't work on anything I would consider "commercial" as it tends to be too dark.
I find writing in itself very therapeutic, as long as I am not writing too deeply about myself or anything too personal. If I do, then I find it too overpowering seeing my inner feelings right there in front of me.