My therapist told me about a concept called "accumulating positive experiences" which has been really helping me, so I figured I'd share. You basically try to "collect" positive experiences. Think about what you'd like to do, do those more often, then reflect on your "collection"
You can even make a daily list of your positive experiences. It's about trying to shift your mindset from focusing on bad things in the past (which often leads to depression) and worrying about potential bad things in the future (which often leads to anxiety) to good things now.
Basically the brain is amazing and neuroplasticity can work in your favour sometimes. When you create new neural pathways by focusing on positive things and actively try to use those pathways more often, you get your brain used to using them and positivity becomes more automatic.
I know mental illness is a complicated thing and this might not work for everyone, but it's a strategy that really helped pull me out of a depression I was sinking deep into a couple weeks ago. Also spending time away from Twitter does help lol