>Use the 20-20-20 rule. Every 20 minutes, take a 20-second break and focus your eyes on something at least 20 feet away.

https://opto.ca/eye-health-library/20-20-20-rule

I used to have an app on my work PC that popped up a reminder if it detected 20 minutes of continuous keyboard/mouse activity. I can't remember the name now but if anyone has any recommendations I would love to hear them.