As cliché as it sounds: slow and steady/ one day at a time. Start small, one of the first things I started doing when I realized I was depressed was journaling/ keeping a diary. Try to make your bed every day, then try showering every day, eating healthier, eventually start going to the gym.
Another thing that I only started doing a few days ago is taking vitamin D supplements. I kept hearing all the time “ you need vitamin D”, “you’ll feel better if you get some vitamin D/ sun”. But I’m super white, I always burn and never tan and tbh I’m terrified of getting skin cancer bc that kind of thing runs in my family. So if you’re like me or if you just can’t find the time of day to spend outside, take vitamin D supplements.