If you haven't heard of the 20-20-20 rule, it is a simple rule-of-thumb to remember to look 20 feet away for at least 20 seconds every 20 minutes.
Using a standup workstation during part of the day may also help you because the "activation energy" required to move around and leave your workstation is minimal compared to sitting in a chair.
You can also get a weaker prescription if you have eyeglasses (not sure about contacts) that will help if you stare at a screen all day.
Good point on the 20-20-20 rule. There's an add-on for Firefox which I use for this below [1]. It launches a (rather invasive) fullscreen popup reminder every 20 minutes. Far from perfect, but better than using a loud timer or relying on your distracted brain!
Using a standup workstation during part of the day may also help you because the "activation energy" required to move around and leave your workstation is minimal compared to sitting in a chair.
You can also get a weaker prescription if you have eyeglasses (not sure about contacts) that will help if you stare at a screen all day.