Really people have always worked often just to have food on the table.

For the development of the weekend we must look to the Victorian era. In the Christian world Sunday was traditionally a day of rest and prayer and people mainly had the day off (some people didn't even get that). However in the Victorian period during the industrial revolution there was less need to work all the time to sustain yourself and so people started to be given Saturday off as well for leisure time (though it has been argued it also meant they consumed more stuff thus feeding the economy).

So really you question is the wrong way round.