Why do you stand there idle?

In the Gospel of St. Matthew 20, we hear Jesus tell the Parable of the Workers in the Vineyard. Jesus tells us that the landowner comes to those in 11th hour and asks, "Why do you stand here idle all day?" And he calls them to labor in the vineyard. All who are in Christ are called to labor in His vineyard to produce a great harvest. But what is this labor? We are not called to labor so that we earn our salvation. No, our labor is both a labor within our own souls; a constant movement toward Christ and to cast away all things that stand in the way of our relationship with Him. So, here in the 11th hour, why do we stand in the vineyard idle all day?