I like to read books but sometimes that's too much mental energy for me. Watching TV is tempting, but for me at least, it usually makes me feel worse. I try to do one thing that's "productive." Just one. It can be tiny. And it either gives me momentum to do more, or I get tired and I get back in bed... but I feel better knowing at least I've done something. I also like to take a nice bubble bath, it gives me a reason to get out of bed yet I'm still relaxed and comfortable.
I hope you get to feeling better soon!