When you're not sure what to write for others (e.g., books, articles, etc.) or feel blocked in general, write for yourself. As reported in the online edition of the McGill Tribune, "The process of writing about traumatic events or important events can have beneficial physical and mental health effects," says Carolyn Birnie-Porter, a PhD student at McGill who has researched the therapeutic benefits of journal writing. Much of her research is based on studies by James Pennebaker, a psychology professor at the University of Texas. According to his studies, journal writing can, among other things, improve immune system function and reduce stress levels.
"[The writing] needs to have insight into why it happened," says Birnie-Porter. "Just writing about positive emotions [or] negative emotions … does nothing." Some key words to use that will have a positive effect include "realize" and "understand."
Even if you don't want to commit yourself to keeping a diary or journal regularly, it can help carry you through a lean period of writing and can help your health at the same time.