Luther’s advice on election (Luther: Letters of Spiritual Counsel, Martin Luther, ed. & trans. Theodore G. Tappert, Philadelphia: Westminster Press, 2006):

• “… the highest of all God’s commands is this, that we hold out before our eyes the image of his dear Son, our Lord Jesus Christ. Every day he should be our excellent mirror wherein we behold how much God loves us… In this way, I say, and in no other, does one learn how to deal properly with the question of predestination. It will be manifest that you believe in Christ. If you believe, then you are called. And if you are called, then you are most certainly predestined.” (p. 116)
• “Do you believe what you hear in the preaching of the Word and do you accept it as the truth? … To have faith in him is to accept these things as true without any doubting. God has revealed himself to you. If you believe this, then you are to be numbered among his elect. Hold to this firmly in with assurance, and if you accept the God who is revealed, the hidden God will be given to you at the same time… If we cling to him, he will hold us fast, and he will tear us away from sin and death and will not let us fall.” (pp. 133-134)
• “We should think of [Jesus Christ] daily and follow him. In him we shall find our election to be sure and pleasant, for without Christ everything is peril, death, and the devil, while in Christ [it] is pure peace and joy. Nothing but anxiety can be gained from forever tormenting oneself with the question of election. Therefore, avoid and flee from such thoughts, as from the temptation of the serpent in paradise, and direct your attention to Christ.” (pp. 137-138)