A Voice from the Past - Luther

It must be carefully noted that Paul calls only those righteous who are justified without the Law, through the promise or through faith in the promise. Keeping the Law, therefore, is something fictitious or a fictitious term, which means nothing apart from faith. Those who rely on works of the Law and want to give the appearance of keeping the Law do not keep it; for he draws the universal conclusion that all who rely on works of the Law are under a curse, under which they would not be if they kept the Law. It is indeed true that he who does these things shall live by them, that is, shall be blessed. But where is this man? Nowhere.

Martin Luther, 1483-1546, Lectures on Galatians - 1535, 3:12, (translated and edited by Jaroslav Pelikan, Luther's Works, Concordia Publishing House, 1963, Vol. 26, p. 274)

What are the implications of the fact that we cannot fully keep the Law? Does that mean we should not  try?