If you’re in that kind of depression where everything is blurry and days blend into one another, taking a lot of photos of positive things might help. If your pet does something cute, you ate something good, got a high score, you cleaned your room, the weather was nice… I’m not saying this will fix your depression, it’s just a good reminder that you are in fact living regardless of the depression distorting your memory and making your past seem like fog of sadness and nothing else.
While true, this won’t cure your depression–that is a lifelong thing many of us must struggle with–reminders DO help. They CAN end negative spirals, they DO help root other memories in place, (specific reminders can help untangle memories otherwise lost to over generalization) and can lead to healthier thought process. So definitely. Take pictures of things. Write down cool stuff. Heck, even write down bad stuff. Remembering it as a single incident and not a recurring thing keeps your brain from defaulting to things ALWAYS being that way. Keep a journal if you can. Something being formally rooted in space and time as an isolated incident helps a LOT.