Sometimes ( not very often ) i feel depressed for no reason. what can i do to feel better?

Exercise: Exercise is a great way to get the endorphins flowing and cope with depression. Keeping a journal might be able to shed some light on a possible trigger of the depression as well as provide an outlet for expressing emotions. If you have a problem with insomnia, that alone can cause mood fluctuations. For severe depression or more frequent symptoms, see a mental health professional.