Depression SUCKS. I went through it a few months ago. I'm lucky mine was temporary though, I think it was seasonal depression. Last winter was long and was all over the place, hot cold hot cold... I think it just finally screwed with me by the end. the clock change did me in. I freaking hate that BS, we need to abolish it once and for all. The constant darkness sucks too - clock change does F all to change that. It's dark no matter what. One of the only things I do hate about living here is the near constant darkness for a good part of the year. Was my first time going through seasonal depression though but I think it may be a sign of getting old, and I will have to watch out more now. My dad said he goes through it too. Had no idea. I unfortunately don't have any advice that is guaranteed to work if you're really clinically depressed but for me going for walks and spending more time in the sun (which for me does not need to be that long, like 15 minutes) and also staring at blue light did help. As for sun, UV-B is what is important, so reptile bulbs may help too, I will do that in winter as there won't be any UV-B from the sun. (need to build a contraption to stick my arm in, as you don't want stray UV reflecting back into your eyes) I bought a SAD lamp for at work too. I use it in mornings as it's the only real source of blue light I get as I don't see any day light. It's dark before I get to work, and after, for most of the year. Right now it's in the transition phase, not QUITE dark but getting there. In another month it will be pitch black.
The hardest part, but probably the most effective, is to try to socialize more though. But that is a tough one especially as an older adult. Myself I don't really have lot of IRL friends. Most people our age have their own lives, lot of them have family etc. I don't even have contacts with hardly any of my high school friends, or even college. I have one college friend I keep in touch with a lot but he moved down south. Also made a friend at church years back so hang out a lot with him, but that's pretty much it. It did help me with the depression to actually go hang out more often though. Well it was probably a combination of things. The light therapy, going for walks, socialization and the meds.
Doing stuff that gives a sense of accomplishment helps too, but that's easier said than done, when you are in state of depression you have zero motivation to do hobbies etc. Even gaming or watching a movie feels "meh". At least for me it was like that. I just did not know what to do with myself. Basically had no motivation to live. It was messed up. Had suicidal thoughts but didn't actually want to do it and I knew it was my brain that was messing with me.
Now that I'm out of my depression I've actually been pushing myself to try to always accomplish something on my days off. Not just sit and do nothing. I have a lot of hobbies I want to get into but often not enough motivation to push through, but when I do decide to get off my butt and do something I'll actually get sucked into it and then I will feel great after.
But yeah I'd say the #1 is socialization... as hard as it is, that is probably the main goal you should try for. I'm not perfect on that front myself, I keep saying I should get in touch with cousins and other family my age that I hardly talk to, and we need to actually start hanging out but never do.
As a side note it's crazy how much most people actually do suffer or have suffered from depression. More than half the people I've talked to said they've suffered from it or actively do. Anxiety is another bad one. They sort of go hand in hand. I had mostly depression, but anxiety would kick in too at times.
But yeah hang in there. It's not fun to go through, but there is light at the end of the tunnel.