A sorrowless earthly life is a true sign that the Lord has turned his face from a man, and that he is displeasing to God, even though outwardly he may seem reverent and virtuous.
Concerning fasting, do not grieve, as I have said to you before: God does not demand of anyone labors beyond his strength. And indeed, what is fasting if not a punishment of the body in order to humble a healthy body and make it infirm for passions, according to the word of the Apostle: 'When I am weak, then am I strong' (II Corinthians 12:10).
If you believe in a Divine Providence which determines the earthly fate of everyone and the way by which he is to be saved, you must also believe that the disposition of your life is the most suitable for you in working out your salvation.
Set as a goal the kindling of the fire of the spirit, so that the spiritual fire will burn in your heart and, gathering up all your strength into one, will begin to build your inner man and finally burn up the tares of your sins and passions.
The day will come when you are toiling at self-observation and self-constraint, and the adversary will come up and mumble in your ear, 'This will all happen eventually. You’ve been working hard, now take it easy a little bit!' This is such a tempting suggestion that it does not immediately occur to you that you should counter it, or that it is so bad that however little you give in to it, it will cause such inner disturbance. Indulging yourself is just like a tiny hole in a dam. Once a hole has formed, the dam cannot hold; the water will inevitably destroy it. Indulgence does the same thing inside of us; everything will be dispersed, so it will be necessary to start all over again to restore ourselves. Fear this as your most evil enemy, although he speaks with the sweetest words.
As it is not possible to walk without feet or fly without wings, so it is impossible to attain the Kingdom of Heaven without the fulfillment of the commandments.
At this point the zealous man looks inward, and what do you think he finds there? Ceaseless wandering of thoughts, constant onslaughts from the passions, hardness and coldness of heart, obstinacy and disobedience, desire to do everything according to his own will. In a word, he finds everything within himself in a very bad state. And seeing this, his zeal is inflamed, and he now directs strenuous efforts to the development of his inner life, to controlling his thoughts and the dispositions of his heart. From directions on inner spiritual life he discovers the necessity of paying attention to oneself, of watching over the movements of the heart. In order not to admit to anything bad, it is necessary to preserve the remembrance of God. And so he sets to work to achieve this remembrance. But his thoughts can no more be arrested than the wind; his bad feelings and worthless impulses can no more be evaded than the stench of a corpse; his mind, like a wet and frozen bird, cannot rise to the remembrance of God. What is to be done? Be patient, they say, and go on working. Patience and labor are exercised, but all within remains the same. At last someone of experience is found who explains that all is inwardly in disorder because the forces within are divided: mind and heart each go their own way. Mind and heart must be united; then wandering of thoughts will cease, and you will gain a rudder to steer the ship of your soul, a lever by which to set in movement all your inner world. But how can one unite mind and heart? Acquire the habit of praying these words with the mind in the heart, 'Lord Jesus Christ, Son of God, have mercy upon me'. And this prayer, when you learn to perform it properly, or rather when it becomes grafted to the heart, will lead you to the end which you desire. It will unite your mind with your heart, it will cut off your wandering thoughts, and give you the power to govern the movements of your soul.
There is one method which, if practiced with full attention, will seldom allow anything passionate to slip unnoticed into the heart. This is to examine our thoughts and feelings, so as to discover which they tend: towards pleasing God or towards pleasing ourselves.
The root of good inner order is the fear of God. Preserve this fear within you constantly: it will hold everything taut, and will allow no slackness either in physical members or thoughts, creating a vigilant heart and a sober mind, and allowing no bodily torpor or blurring of thought. But one must always remember that success in any aspect of the spiritual life is the fruit of the grace of God. Spiritual life comes entirely from His most Holy Spirit. We have our own spirit but it is void of power. It begins to gain strength only when the grace of God flows in it.
The reason that fasting has an effect on the spirits of evil rests in its powerful effect on our own spirit. A body subdued by fasting brings the human spirit freedom, strength, sobriety, purity, and keen discernment.
He who has not received within himself the kingdom of God cannot recognize the Antichrist. He is absolutely sure to become in a way incomprehensible to himself his follower.
Those who have acquired genuine prayer experience an ineffable poverty of the spirit when they stand before the Lord, glorify and praise Him, confess to Him, or present to Him their entreaties. They feel as if they had turned to nothing, as if they did not exist. That is natural. For when he who is in prayer experiences the fullness of the divine presence, of Life Itself, of Life abundant and unfathomable, then his own life strikes him as a tiny drop in comparison to the boundless ocean. That is what the righteous and long-suffering Job felt as he attained the height of spiritual perfection. He felt himself to be dust and ashes; he felt that he was melting and vanishing as does snow when struck by the sun's burning rays (Job 42:6).