First make yourself unbeatable, then wait for the enemy to become beatable

The Art of War · Sun Tzu

Build an impenetrable fortress of the mind that no external force can breach

The Daily Stoic 366 Meditations on Wisdom, Perseverance · Ryan Holiday and Stephen Hanselman

Choose what matters, ignore what doesn't, and become invincible

The Subtle Art of Not Giving a F ck (The Subtle Art of Not · Mark Manson