Being determined to maintain a positive outlook is worthy and something I think a lot of people need to do, but it's far too pat to blame depression on improper thinking.
It has been proved that there is a close link between pain and depression: longterm of either causes the other. This article touches on that:
Harvard Article Also, this article:
Hopkins Article I don't know how I missed this article, as it seems to support my theory that biologics could be used to treat chronic depression:
Enbrel & Depression And then there's this:
Annals of General Psychiatry My point is, that while you are right we need to combat the lure of seeing ourselves as ill and pain-ridden, there is much more to it than that. I admire your drive to rid yourself of negative thought, and that is most certainly a tool that people living with chronic pain and chronic depression could do well to work with, but you cannot just generalize and assume that all people who are depressed, or pain ridden, are just thinking incorrectly. There is an actual, physical connection between pain and depression.
Situational depression is a different thing altogether, and very often will resolve as the situation that causes it resolves. In this case, positive thought, sometimes paired with anti-depressant medication, will help.
Hugs,