I'll start with a warning that this comment is just my humble opinion. First I'll say that I pretty much agree with what you posted and I can't really argue against it because what you posted is pretty much true.
However with that said , the first thing that came to mind when I read the title was 'Ouch' :) . And while the title is true in some sense(depending on how you look at it) , it's probably not something you want to tell to a person that is suffering from depression. In doing so would either pull them out of the darkness they are in or ... push them further down into it (again in my humble opinion)
Also , I think your advice on dealing with stress is a good one , but also can be applied to what are considered negative emotions. In that , instead of ignoring them or avoiding them that one can allow oneself to feel it but not get lost in them. I tend to believe that we are all made up of positive and negative , or light and dark , or however you want to put it, and we have the potential to be either at any given moment. And the flip side of what is positive is part of what makes us human. I would tend to think that avoiding , ignoring or denying that the negative exists would do more harm than good in the long term. In that , sometimes one needs to experience the darkness or negative to be able to learn how to deal with it or get out of it as the case may be. (again just my opinion , however I am speaking from personal experience on that one.)
And in saying all that , I do see your post as a positive one and a good post , so thank you for posting this. :)
Thank you, thank you, Thank you. This is the first comment I've seen on here to bring up depression. It is most certainly not my fault that my brain literally doesn't receive dopamine the way it's supposed to, meaning I'm constantly struggling with being happy.