Understand: your mind is weaker than your emotions. But you become aware of this weakness only in moments of adversity — precisely the time when
you need strength. What best equips you to cope with tthe heat of battle is neither more knowledge nor more intellect. What makes your mind stronger, and more able to control your emotions, is internal discipline and toughness.No one can teach you this skill; you cannot learn it by reading about it. Like any discipline, it can come only through practice, experience, even a little suffering. The first step in building up presence of mind is to see the need for ii — to want it badly enough to be willing to work for it.

[T]hose who are difficult to move, but on that account susceptible of very deep feelings, men who stand in the same relation to the preceding as red heat to a flame, are the best adapted by means of their Titanic strength to roll away the enormous masses by which we may figuratively represent the difficulties which beset command in War. The effect of their feelings is like the movement of a great body, slower, but more irresistible.

[...] We therefore say once more a strong mind is not one that is merely susceptible of strong excitement, but one which can maintain its serenity under the most powerful excitement, so that, in spite of the storm in the breast, the perception and judgment can act with perfect freedom, like the needle of the compass in the storm-tossed ship.

Either way, mental strength is not just hoping that nothing ever goes wrong. It is believing that we have the capacity to handle it if it does.

We repeat again: strength of character does not consist solely in having powerful feelings, but in maintaining one’s balance in spite of them. Even with the violence of emotion, judgment and principle must still function like a ship’s compass, which records the slightest variations however rough the sea.

What is here required from the higher powers of the mind is a sense of unity, and a judgment raised to such a compass as to give the mind an extraordinary faculty of vision which in its range allays and sets aside a thousand dim notions which an ordinary understanding could only bring to light with great effort, and over which it would exhaust itself. But this higher activity of the mind, this glance of genius, would still not become matter of history if the qualities of temperament and character of which we have treated did not give it their support.

Truth alone is but a weak motive of action with men, and hence there is always a great difference between knowing and action, between science and art. The man receives the strongest impulse to action through the feelings, and the most powerful succour, if we may use the expression, through those faculties of heart and mind which we have considered under the terms of resolution, firmness, perseverance, and force of character.

A strong body makes the mind strong... I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind.

... a strong character is one that will not be unbalanced by the most powerful emotions

I believe we are powerful, but we don’t use our minds to full capacity. Your mind is powerful enough to help you attain whatever you want.

Strength is not a roar of thunder in the heart.
That is passion
Strength is not a process of logic in the mind.
That is reason.
Strength is a soul-deep voice that whispers
'keep going' when we feel like giving up.

You have control over your mind — not outside events. Realize this, and you will find strength. — Roman emperor Marcus Aurelius, Meditations

Clarity of mind means clarity of passion, too; this is why a great and clear mind loves ardently and sees distinctly what it loves.

A man who is of 'sound mind' is one who keeps his inner madman under lock and key.

it has been your thoughts that have made you feel alternately weak and strong.’ My guru looked at me affectionately. ‘You have seen how your health has exactly followed your subconscious expectations. Thought is a force, even as electricity or gravitation. The human mind is a spark of the almighty consciousness of God. I could show you that whatever your powerful mind believes very intensely would instantly come to pass.’ “Knowing

There is no limit to the power of the human mind. The more concentrated it is, the more power is brought to bear on one point