Agricultural work is seasonal. For most of the year you aren't working in the fields. Yes planting and harvesting can require longer hours because you need the planting and harvest done as fast as possible in order to maximize yield and reduce spoilage, but you aren't harvesting and planting the fields for the entire year working non-stop. And even then most people worked at their own pace, not every farm was as labor productive as another or even had to be as productive. Some people valued their time and health and comfort, some people valued being able to brew more beer with their 5% higher yield, some valued leisure time more, but it was a personal choice that people made. The industrial revolution is the outlier point in making people work long non-stop hours all the time. Living a subsidence farming lifestyle doesn't mean you are just hanging on a bare thread of survival the entire time like a lot of pop-media likes to portray.