Depression is tough. I've spent many days depressed. I believe it's mainly chemical. Under normal circumstances we have the coping skills (with training or development) to deal with depression. I also believe that once healthy we can choose happiness. It's all up to how we want to live our day. Do we want to react sadly or do we want to be an observer and not pass judgement. I try to let things go as much as I can. Sometimes I do feel sad. I acknowledge that, feel it and then move on. Feelings are meant to be felt. Not feared or pushed away.