Other people's lack of understanding of how I am feeling.

Not that I blame them as until you have suffered a serious depressive episode you can't really understand what it is like. I was a Registered Mental Nurse (RMN) for over 20 years before becoming ill and I thought I had a fairly good understanding of depression. I knew what the signs and symptoms were and how to talk with someone experiencing them. I knew what the treatments were and how an episode might progress. I had no real understanding though of how it felt to be the person experiencing this hideous, horrendous condition.

I doubt that, even now, I could adequately explain how it feels. I could go on at great length about every horrible element to my experience of depression but nothing I could say could possibly get across how soul crushingly bad it can feel. (There have been times when I would honestly have swapped it for something as awful as bone cancer if I could.) Even if I were the most eloquent person in history and you the most empathetic though you still wouldn't understand how I felt. So, if you are dealing with someone suffering from a mental illness, please don't tell them that you understand how they feel. With the best will in the world, you don't. Just let them know that you are there for them. Listen when they want to talk. Help out with anything practical they might ask of you, if you reasonably can. But mostly just let them know you are there and are not going to judge them.