Fear of starvation.
For some colonies it is referred to as the Protestant Ethic or the Protestant Work Ethic or The Puritan Work Ethic.

The Protestant Work Ethic is also known as the Puritan Work Ethic. It emphasizes hard work, frugality and diligence. It requires consistently showing one has acquired salvation through Christianity, and shifts the emphasis from Catholic qualities such as confession and sacrament.

An ethic means a principle (e.g. "Protestant work ethic") while Ethics is the study of moral philosophy. QED.

Protestant Ethic

They worked 6 days a week.