Would you be willing to share what, if anything, triggers your depression (or other pain)? I know depression often comes for no apparent reason, but can be made far worse by something beyond one's control (which is also a trigger in my mind).
Personally, I didn't think I had triggers, but someone's comments tested this. Specifically, she mentioned what a wonderful experience childbirth had been for her, because her kids gave her meaning and purpose in life where there had been none. I know I should've been happy for her, but instead felt the burden of loneliness on my own part. It's as though she considered life meaningless unless you're a parent.
I realize others (especially parents) are dealing with other issues and this will not be something to identify with... but any triggers you might have would be relevant.