I can tell if I’ve been sitting at the computer too long. And I cant stand that feeling. Unfortunately, because of my job, sometimes I’m stuck there for a while. I would definitely advise taking some long walks outside if that’s possible, to break it up.
Plus, your eyes are trained on the screen when you are at the computer, and that’s not good. Apparently, focusing on one thing for too long strains the muscles in your eyes, but looking around, focusing off into the distance and then on something nearby, looking left to right, all of that helps the muscles in your eyes. That’s my biggest thing is when I start to feel that eye strain. That’s why I suggest going outside. There’s so many things to look at, you would be hard pressed to strain your eyes looking at any one thing outside.