Here is a talk by President Hinckley from the New Era magazine, July 1999. I used this article in a lesson that I taught the Young Women.
Words of the Prophet: Blessed Are the Pure in Heart by President Gordon B. Hinckley
My young friends, “Be not faithless, but believing”—in virtue, in goodness, in decency, in purity, in that which the Lord has declared He would have for His children, virtue. It is old-fashioned. It may appear out-of-date. It does not square up with a lot of thinking and teaching, but it is true.
There is nothing lovelier, there is nothing sweeter, there is nothing finer, there is nothing more ennobling, there is nothing more beautiful in all the world than virtue in young men and women. God has designed that it should be so. “Be not faithless, but believing.” And in the light of that belief, and in the light of that faith, practice discipline (from Brigham Young University Speeches, Jan. 3, 1962, 5).
Blessed are the pure in heart
Youth is the seedtime for the future flowering of family life. To hope for peace and love and gladness out of promiscuity is to hope for that which will never come. To wish for freedom out of immorality is to wish for something that cannot be. Said the Savior, “Whosoever committeth sin is the servant of sin” (John 8:34).
Is there a valid case for virtue? It is the only way to freedom from regret. The peace of conscience which flows therefrom is the only personal peace that is not counterfeit.
And beyond all of this is the unfailing promise of God to those who walk in virtue. Declared Jesus of Nazareth, speaking on the mountain, “Blessed are the pure in heart: for they shall see God” (Matt. 5:8). That is a covenant, made by Him who has the power to fulfill (from Conference Report, Oct. 1970, 66).
Lure of immorality
I am going to speak plainly. We hear much these days of teenage sexual misbehavior. There is too much of it among our own youth.
Those who indulge in illegitimate sexual activity, as we define that in the doctrines and standards of this Church—and I think no one misunderstands what I mean when I say that—do irreparable damage to themselves and rob the one with whom they are involved of that which can never be restored. There is nothing clever about this kind of so-called conquest. It carries with it no laurels, no victories, no enduring satisfaction. It brings only shame, sorrow, and regret. Those who so indulge cheat themselves and rob another. In so doing, they affront their Father in Heaven, for they are children of God.
I know that this is strong language, plainly spoken. But I feel the trends of our times call for strong language and plain words (from Ensign, Nov. 1983, 45).
Let virtue be your cornerstone
In April of 1942, the First Presidency of the Church issued a message that has the tone of scripture. I commend it to you:
“To the youth of the Church … above all we plead with you to live clean, for the unclean life leads only to suffering, misery, and woe physically—and spiritually it is the path to destruction. How glorious and near to the angels is youth that is clean; this youth has joy unspeakable here and eternal happiness hereafter” (Improvement Era, 45:273).
You of marvelous promise, you young men and women of great ability, do not mock God. Do not flout his law. Let virtue be a cornerstone on which to build your lives (from Conference Report, Oct. 1964, 116).
I would just like to say a word about pornography. It is a growing, vile, and evil thing. It is on our motion picture screens, it comes into the homes of the people on television receivers, it is on newsstands, it reaches out in other ways to entrap and beguile and destroy those who are enticed to partake of it. I am satisfied, my brethren and sisters, that no Latter-day Saint can with impunity afford to witness or read or partake of this growing evil in any way. God help us and bless us with the self-discipline to resist and abstain and flee from, if necessary, this pernicious and growing thing which would destroy us (from Ensign, Nov. 1982, 76).
Control thoughts to control actions
Mental control must be stronger than physical appetites or desires of the flesh. As thoughts are brought into complete harmony with revealed truth, actions will then become appropriate.
The timeless proverb is as true now as when it was first spoken: “For as he thinketh in his heart, so is he” (Prov. 23:7).
Each of us, with discipline and effort, has the capacity to control his thoughts and his actions. This is part of the process of developing spiritual, physical, and emotional maturity (from Ensign, May 1987, 48).
Repentance and forgiveness
If there be any here who have so sinned, there is repentance and there is forgiveness, provided there is “godly sorrow” (2 Cor. 7:10). All is not lost. Each of you has a bishop, who has been ordained and set apart under the authority of the holy priesthood and who, in the exercise of his office, is entitled to the inspiration of the Lord. He is a man of experience, he is a man of understanding, he is a man who carries in his heart a love for the youth of his ward. He is a servant of God who understands his obligation of confidentiality and who will help you with your problem. Do not be afraid to talk with him (from Ensign, Nov. 1983, 45).
Prove your strength
For your own sakes, for your happiness now and in all the years to come, and for the happiness of the generations who come after you, avoid sexual transgression as you would a plague.
Prove your strength, show your independence, by saying no when enticement from peers comes your way. Your own strength will add strength to those who are weak. Your own example will give determination to others (from Ensign, May 1987, 48).
Stay on the Lord’s side
Of course you are to socialize, to date, to have fun of a wholesome kind in a hundred ways. But there is a line which you must not cross. It is the line that separates personal cleanliness from sin. I need not get clinical in telling you where that line is. You know. You have been told again and again. You have a conscience within you. Stay on the Lord’s side of the line (from Ensign, May 1996, 48).