I highly recommend using an app like http://breaktimeapp.com http://breaktimeapp.com. You set an interval and length of breaks and Breaktime will lock your scr

I highly recommend using an app like http://breaktimeapp.com http://breaktimeapp.com. You set an interval and length of breaks and Breaktime will lock your screen so you are forced to rest your eyes. Use it to look outside the window every once in a while. As a tip, definitely enforce the break. You are always tempted to get out of it if you don't.