I've find keeping mental health is kinda like keeping sobriety. Even when you've been clean for years, you have to keep the habits up, keep the self-care up, or you risk a relapse.

I've been through this mill a few times, now. My three main priorities become sleep, exercise and eating, because all three go out the window when I'm depressed.

I make some things 'non-negotiable'. Some food must be eaten that day. I must shower. Some kind of exercise, even if I just do laps of the apartment. I don't bother with cajoling or arguing or reasons why it should be done: I try to make them as much a fact as possible, and borrow my mother's phrase of "you don't have to like it, you just have to do it".

I've found the non-negotiable thing incredibly useful, but I don't really know how to explain how I do it it to others. I managed to finish my masters' degrees in the depths of one of my worst depressions, because I made everything to do with my degree non-negotiable. I did the same for my business last year: my billable work was non-negotiable. It's not discipline so much as removing the possibility for arguing from your brain. It's just not an option for this to not get done, the way it's not an option to stop gravity. The fact that I don't have to spend mental energy "convincing" myself to do it makes things that much easier, but it's a weird little find-the-lady brain-game. The closest I can get to an explanation is just turning off the part of your brain that would debate not doing it.

I reread my CBT and ACT books to remind myself of the tools that I've learned to help the symptoms. I put little safety plans in place, with objective-as-possible triggers: "if it gets so bad that [I start worrying my brain will think me to death] I will do THIS." Having those plans in place helps me panic less about how bad things might get.

I journal the day's thoughts to myself. It helps me see a little where my depression is not making sense, just making me think that it does. I find it really important to recognise daily that this is an illness I currently have: it helps me not panic (and to feel less broken and hopeless) about the fact that I don't care one iota about any of the things I normally care about. Making it okay to not be okay right now is something I find very helpful, helps me not beat myself up over not being better yet.

I try to put visual art and living things in my life more–daily, if possible. I make things, I reorganise my craft supplies, I sort my bookshelves, I go buy a cactus, I go hang out with somebody's cat and cuddle it. And I'm very, very careful of what art I consume.