'Exertion' in the Bible

I have seen the task which God has given to the sons of men with which to occupy themselves.

From the days of John the Baptist until now the kingdom of heaven suffers violent assault, and violent men seize it by force [as a precious prize].

So then God’s choice is not dependent on human will, nor on human effort [the totality of human striving], but on God who shows mercy [to whomever He chooses—it is His sovereign gift].