How good is It should not be too hard. If you need to work hard for several days. Find the time to 10-20 minutes to the eyes or one eye to take five minutes to walk and breathe fresh air. But the best thing is that you get adequate rest for at least 6-8 hours a day for good health, ready for hard work. And do not forget to find time to relax on vacation with your family to good relations in the family.