I feel tired even though I haven't done anything all day

My routine is basically using the internet with breaks just to eat and maintain my hygiene. Other than that, I don't do anything that requires any effort. I feel tired even when I try to do easy things, like playing video games, watching series or drawing. I've also lost the desire to consume adult content, but I force myself to do so because it's one of the few stimuli that still gives me some emotion. At this point I'm practically a zombie. But instead of devouring brains, I'm destroying mine.