I also found I could code for about 4 hours, so after that I like to reply to messages and read and sketch out ideas for how to approach bugs on paper, just get off the screen. And after a while of that I’ll go for a walk or something and maybe circle back around to the code if I thought of something.
I don’t mind this at all, 8 hours of screen time is a killer and no doubt led to my bad eyesight and wonky posture staring at screens when I was younger.