Lately in the Western world it has become normative for sadness to be equated with pathology. When people realize that they have been feeling sad or melancholy for a while they become concerned that it means they are depressed or something is wrong. However emotions are not "bad," and they do not have to define who we are. Just because we have certain thoughts or feelings does not mean we are those thoughts and feelings. It is true though that the actions we choose to take or, which end up taking over us are the result of the information we filter from our emotional states. Becoming aware of the functions of emotions and the information they are meant to provide can contribute to healing in a unique kind of way that is often found in having compassion for oneself.
Check out this latest TED-ED Animation by Courtney Stephens discussing the role of sadness in our lives.