Be kind to yourself
Humanity was fucked before you were even born. It's not your responsibility to fix it. Do what you can to make things better, but don't get upset if it seems like you aren't making a difference. Never feel guilty about indulging in things you enjoy or taking a break.
Life is a accident of chance and circumstance. We didn't get to choose to be alive now — at this moment in history, in this place, under these conditions, etc. We just have to deal with it all as best we can
Humans are dumb. We are a bunch of fuckups and misfits. It's surprising we've made it this far. But we've survived some crazy shit. Maybe we'll survive this too.
The planet will live on regardless. Or not. Doesn't matter. In a few billion years the sun will expand and burn it to a cinder.
Doesn't change the fact that you have to live your life right now.
Kiss your partner. Play a video game. Chat with a friend. Help a stranger. It's all still good even if it's meaningless. Savor the good.