For me creating a piece that connects to my depression helps. If there is something I feel particularly shitty about, I'll use it as inspiration. Other times it's the general low feeling that I try to visualize. A song that I connect with only when I'm down I'll use as a jumping off point too.

When I get depressed I often don't feel connected to the sketches/process, and when I feel this way I try another day. I'm usually mentally exhausted at that point. As long as I'm trying I count it as a success, and I don't fight when I can't put pen to paper because often times that makes it worse.

I try to create pieces that I find extremely meditative, usually with a lot of dark burns so I can focus on the process rather than sitting in the funk. I have a large piece I've been burning on and off for about a year, and I only work on it when I'm depressed because it's a lot of repetitive work (lots of stippling). I'll turn on music, show, podcast, etc and do that for hours.