Satiety in food is the father of fornication

Venerable John Climacus ~ The Ladder of Divine Ascent
Step 14 ~ On Gluttony

¶5. Satiety in food is the father of fornication; but affliction of the stomach is an agent of purity.
¶6. He who fondles a lion often tames it, but he who coddles the body makes it still wilder.

Cutting off thoughts

Venerable John Climacus ~ The Ladder of Divine Ascent
Step 15 ~ On Purity and Chastity

¶74. The discerning Fathers have defined that assault is one thing, converse another, consent another, captivity another, struggle another, passion so-called in the soul, another. And these blessed men define assault as a simple conception, or an image of something encountered for the first time, which has entered the heart. Converse is conversation with what has presented itself, accompanied by passion or dispassion. And consent is the bending of the soul to what has been presented to it, accompanied by delight. But captivity is a forcible and involuntary rape of the heart, or a permanent association with what has been encountered which destroys the good order of our condition. Struggle, according to their definition, is power equal to the attacking force, which is either victorious or else suffers defeat according to the soul’s desire. Passion, they say, is preeminently that which for a long time nestles with persistence in the soul, forming therein a habit, as it were, by the soul’s longstanding association with it, since the soul of its own free and proper choice clings to it. Of all these states, the first is without sin, the second not always, but the third is sinful or sinless according to the state of the contestant. Struggle is the occasion of crowns or punishments. Captivity is judged differently, according to whether it occurs at the time of prayer, or at other times; whether in things indifferent [neither good, nor bad], or in the case of evil thoughts. But passion is unequivocally condemned in every case, and demands either corresponding repentance or future punishment. Therefore, he who regards the first assault dispassionately cuts off at a single blow all the rest which follow.

When we are lying in bed, let us be especially sober and vigilant

Venerable John Climacus ~ The Ladder of Divine Ascent
Step 15 ~ On Chastity

¶53. When we are lying in bed, let us be especially sober and vigilant, because then our mind struggles with the demons without our body, and if it is sensual, it readily becomes a traitor.
¶54. Always let the remembrance of death and the Prayer of Jesus, being of single phrase, go to sleep with you and get up with you; for you will find nothing to equal these aids during sleep.

The place in which we are attacked

Venerable John Climacus ~ The Ladder of Divine Ascent
Step 15 ~ On Chastity

¶62. As we have said before, some people in hermitages suffer far more severe attacks from the enemy. And no wonder! For the demons haunt such places, since the Lord in His care for our salvation has driven them into the deserts and the abyss. Demons of fornication cruelly assail the hesychast in order to drive him back into the world, as having received no benefit from the desert. Demons keep away from us when we are living in the world, that we may go on staying among worldly-minded people because we are not attacked there. Hence we should realize that the place in which we are attacked is the one in which we are certainly waging bitter war on the enemy; for if we ourselves are not waging war, the enemy is found to be our friend.