I know this probably sounds stupid and/or obvious but one of the easiest and most effective way to combat depression is to literally go outside and exercise. Just get up and go for a walk, or do push-ups or go for a run or something. Like, even if you're not very good at it, you can try to run as far as you can and make a game out of it trying to go further and further each day (same idea applies to push-ups or whatever else as well)
Idk your situation but I think pretty much anyone can benefit from more regular exercise, if only by feeling a little bit better about yourself. I personally didn't exercise hardly at all but I made a point to go for a run every day regardless of how I'm feeling, and even though I kinda sucked at it at first (would have to stop and catch my breath all the time) as I kept doing it I got a lot better and it felt good to keep pushing myself to go further and further. It made it easier to fall asleep at night cause I would be physically exhausted and too tired to stay up all night (fuck insomnia)
Also meditation is another good way to deal with depression, helps to recognize your negative thoughts as just thoughts instead of believing them to be some objective truth.