A car needs maintenance regularly, e.g. change lubricating oil, change air filter, oil filter, brakes etc.
A car will not last long if it is given no rest. So is our human body.
The followings are teachings of LORD about rest.
During period of rest, our body will repair itself, much like a patient recover in a hospital.
LORD : "Six days you shall do your work, but on the seventh day you shall rest; that your ox and your ass may have rest, and the son of your bondmaid, and the alien, may be refreshed." [Ex. 23:12]
LORD : "Three times in the year you shall keep a feast to me. You shall keep the feast of unleavened bread; as I commanded you, you shall eat unleavened bread for seven days at the appointed time in the month of Abib, for in it you came out of Egypt. None shall appear before me empty-handed. You shall keep the feast of harvest, of the first fruits of your labour, of what you sow in the field. You shall keep the feast of ingathering at the end of the year, when you gather in from the field the fruit of your labour. Three times in the year shall all your males appear before the LORD GOD." [Ex. 23:14-17]
LORD : "For six years you shall sow your land and gather in its yield; but the seventh year you shall let it rest and lie fallow, that the poor of your people may eat; and what they leave the wild beasts may eat. You shall do likewise with your vineyard, and with your olive orchard." [Ex 23:10-11]
LORD : "And you shall count seven weeks of years, seven times seven years, so that the time of the seven weeks of years shall be to you forty-nine years. Then you shall send abroad the loud trumpet on the tenth day of the seventh month; on the day of atonement you shall send abroad the trumpet throughout all your land. And you shall hallow the fiftieth year, and proclaim liberty throughout the land to all its inhabitants; it shall be a jubilee for you, when each of you shall return to his property and each of you shall return to his family. A jubilee shall that fiftieth year be to you, in it you shall neither sow, nor reap what grows of itself, nor gather the grapes from the undressed vines. For it is a jubilee; it shall be holy to you; you shall eat what it yields out of the field." [Lev 25:8-12]
LORD : "When a woman has a discharge of blood which is her regular discharge from her body, she shall be in her impurity for seven days, ...." [Lev 15:19]
LORD : "Say to the people of Israel, If a woman conceives, and bears a male child, then she shall be unclean seven days; as at the time of her menstruation, she shall be unclean. And on the eighth day, the flesh of his foreskin shall be circumcised. Then she shall continue for thirty-three days in the blood of her purifying; she shall not touch any hallowed thing, nor come into the sanctuary, until the days of her purifying are completed. But if she bears a female child, then she shall be unclean two weeks, as in her menstruation; and she shall continue in the blood of her purifying for sixty-six days." [Lev 12:1-5]
(Note : one would argue that one cannot afford so many days of rest. But if you buy fewer things, e.g. clothes, shoes, ... etc. you can. Do not pursue after expensive clothes, but pursue after kindness, mercy, love, .... you will live happier this way.
Sometimes, because of duty or otherwise, we have to work continuously for a period of time without rest. Then we calculate the number of days to rest on the basis of one day per week, and rest accordingly afterwards. (Say, if you have to work overtime for 2 months, unable to rest on Sundays, then you should take 8 days rest (8 weeks in 2 months) after that.)
WARNING : Do not worry too much about your own body, as Lord Jesus taught us, and we should concentrate on righteousness. Also, caring too much about our body may be a snare to us, as Lord Jesus taught us to love his teachings more than our life :
Jesus : "Therefore I tell you, do not be anxious about your life, what you shall eat or what you shall drink, nor about your body, what you shall put on. Is not life more than food, and the body more than clothing? Look at the birds of the air; they neither sow nor reap nor gather into barns, and yet your heavenly Father feeds them. Are you not of more value than they? And which of you by being anxious can add one cubit to his span of life? And why are you anxious about clothing? Consider the lilies of the field, how they grow; they neither toil nor spin; yet I tell you, even Solomon in all his glory was not arrayed like one of these. But if God so clothes the grass of the field, which today is alive and tomorrow is thrown into the oven, will he not much more clothe you, O men of little faith? Therefore do not be anxious, saying, 'What shall we eat?' or 'What shall we drink?' or "What shall we wear?' For the Gentiles seek all these things; and your heavenly Father knows that you need them all. But seek first his kingdom and his righteousness, and all these things shall be yours as well." [Mt 6:25-33]