I hate to say it, but this really seems to be different for everyone.
Personally I only have to deal with situational depression, though this can easily be made worse by a my struggles with anxiety. I have many loved ones in my life struggling with depression and other forms of mental struggles. It is an important and, unfortunately, overlooked problem in our society. There is so much that goes into this I don’t really know where to begin.
Depression, Bipolar disorder, and other mental struggles have been such a part of my life I guess it was unavoidable that my characters would end up facing similar trials.
Not sure if any of this rambling is actually important, but I would love to see more people commenting and discussing on this thread. It’s so very important.