I feel like I'm going to turn into a hunchback, and on some occasions I can feel my eyes pulsating from staring at the screen for too long. And I don't get any exercise.

try raising and lowering your seat...I stare at computer screens all day too, and I find that viewing from a different angle after a while, even if it's just an inch drop in the height of the seat, helps a ton, at least for me!

I think ideally your line of sight is completely level with the center of your computer screen, so that you're not staring up or down all the time.

I'll try seat adjustments though.

yes..dead on is ideal. but even that hurts after a while. I think muscle confusion works best for me.