As someone who is struggling with extreme, literally disabling depression that has continued for over 20 years... This is always a major issue. On good days, I try to play video games to distract myself from reality, most days I read some to get my brain into other worlds which lets me think about how to solve issues there instead of focusing on real life. Meditation is a huge help, as is finding the proper music. I highly recommend listening to Weightless and Top of The Morning by Mike Oldfield, and almost anything by Amethystium, those are very good for calming a turbulent mind.
Personally, I haven't found leaving my apartment to help at all, but many people find that walking or exercising help a great deal. Additionally, friends can help, but it is very easy to find 'bad' friends instead. You want people who accept that you are having problems and support you, and remind you that what you manage is good, even if it isn't much. Unfortunately, many will try to push you, which can have very negative impact, despite their good intentions.
Futhermore, if you just can't handle a day, go to sleep, and if needed, take sleep... forget the word, stuff like melatonin to help you get to sleep. Sleeping is a kind of hard-reset of the brain, which can cut off feedback loops that cause harm. Similarly, if you get caught in a feedback loop, try to find something to break it, such as if you feel bad about not doing anything, try just doing the dishes or making food for tomorrow in advance, then focus on having accomplished something.
I'd also highly recommend writing, as I very much enjoy it, but it can be extremely difficult to manage enough motivation, and you don't want to make yourself feel worse by not doing something due to low motivation. Another thing that I find helps is to try to help others by giving advice, such as this post itself.
Hopefully this helps at least one other person with similar issues - I don't want anyone to suffer a similar state of mind.
