"The Kingdom of Heaven suffereth violence, and the violent take it by force" (Matthew 11:12). If we do not daily strive to conquer the passions, which fight against us, and to gain the Kingdom of God in our heart, then the passions will tyrannically, forcibly take possession of us, will invade our soul like robbers; our attachments to earthly things will increase in proportion as our faith in heavenly blessings and love for God and our neighbor will also grow weaker and weaker; we shall enjoy rest of conscience and peace of heart more and more seldom. We must struggle in the matter of salvation of the soul, which is more precious than anything in the world; we must count everything earthly as dross, or as a phantom, a vision, and everything heavenly, above all, the Lord Himself, as truth itself, eternal, most blessed, and unchangeable.
St. John of Kronstadt
"My Life in Christ"