You can use the promodoro technique. It will increase your productivity, spark creativity and also protect your eyes from the monitor.
Just go to http://tomato-timer.com/.
Click the "promodoro" button and start working your stuff for 30 minutes and concentrate only on that work.
After 30 mins, the promodoro timer will alarm and you need to stop what you're doing.
Click the short or long break button, this is the time you rest your eyes, drink water, take a walk or surf the internet for distraction.
Rinse and repeat until the work is done.
With this, I can work on the hard stuff of my projects easily while staying healthy.