Flow- I am no expert on DB, but I have a lot of second AND first-hand knowledge of depression that has come with feelings similar to what you're describing, and just want to say that even though it may not feel like it's helping you, it is. Somewhere in your brain, maybe a part that's a little dormant and needs a kickstart, you are collecting these activity experiences and it's building postive stuff, I'm sure of it. Keep plugging away, even if it just feels like going through the motions- I know your feelings well and could write volumes about it.
My other belief - from personal experience and doing a lot of thinking about it- is that when you do *anything* distracting that gives your brain a break from its depressing or anxious thoughts and worries, that that time provides a little bit of healing. It doesn't matter if you feel bad again right when you stop- if you can do something to distract- better yet, temporarily lose yourself like in a good book or movie, I have always felt like it heals you a tiny bit - gives your brain the rest it needs to keep going and get stronger. Not a great analogy, but you know how doctors sometimes keep brain injury patients in a medically-induced coma to give the brain time to heal? I'm not suggesting anyone drug themselves, but those little distractions that take you out of that bad place for a little while help, even if it doesn't feel like it right now.
Hug to you-
When the men on the chessboard Get up and tell you where to go; And you've just had some kind of mushroom And your mind is moving slow; Go ask Alice... I think she'll know.
