We have to live not willing to enter into any venial sin, to not desire them.
‘To abstain from sinful actions is not sufficient for the fulfillment of God’s law. The very desire of what is forbidden is evil.’
St. John Baptist de la Salle
‘. . . it is certain that, so long as the guilt of venial sin is not remitted, the punishment due to it cannot be remitted.’
St. Alphonsus Maria de Liguori
The guilt of venial sin is not remitted as long as there is not repentance. There is not repentance as long as there is attachment. So, hate sin, hate temptations do not delight in them, and love God.
If you do not hate sin, you do not love God. But with hatred of sin you can overcome sin and so love God.
All the ‘goods’ offered in temptations are emptiness and void, and worse, because they are nothing compared to God.
So the method for freedom from all attachment to sin is hatred of all sin, and love of God.
This method is achieved by constant thought of God, and recourse to His graces.
'I have come to teach you the prayer which I made as a young girl when I was still living in the Temple. I resolutely decided in my heart that I wished to have God as father and I made up my mind to do whatever would please him, so that I might find favour in his sight. I made myself learn his law and all the commandments contained in it. In particular I committed to memory three commandments, being eager to keep them with the greatest care and with all my might. These are: ‘Love the Lord your God with all your heart and with all your soul and with all your strength. Love your neighbour as yourself. (Dt 6:5) Love your friend and hate your enemy." (Lv 19:18 and Mt 5:3) For I understood that man and angel were good, and my enemy was the devil and, insofar as he is evil, the evil man. From that love of God and neighbour, and from the fear and hatred of the enemy (that is, of the devil and sin), every fulness of grace and virtue has descended to me. That love cannot take root in the human heart unless there is there hatred of the enemy, that is, of the devil and sin.’
The Blessed Virgin to St. Elizabeth, from ‘The Revelations of St. Elizabeth of Toss’
‘Prayer is, beyond doubt, the most powerful weapon the Lord gives us to conquer evil passions and temptations of the devil; but we must really put ourselves into our prayer: it is not enough just to say the words, it must come from the heart. And also prayer needs to be continuous, we must pray no matter what kind of situation we find ourselves in: the warfare we are engaged in is on-going, so our prayer must be on-going also.’
‘God knows how useful it is to us to be obliged to pray, in order to keep us humble, and to exercise our confidence; and he therefore permits us to be assaulted by enemies too mighty to be overcome by our own strength, that by prayer we may obtain from his mercy aid to resist them;’
‘What shall we then do, my brethren? Do you not see that God is angered? He can no longer bear with us. The Lord is angry. Do you not behold the scourges of God increasing every day? Our sins increase, says St. John Chrysostom, and our scourges increase likewise. God, my brethren, is wrathful: but with all his anger he has commanded me to say, what he formerly commanded to be said by the prophet Zachary: And thou shall say to them, Thus says the Lord of Hosts: Turn to Me says the Lord of Hosts, and I will turn to you says the Lord of Hosts. Sinners, says the Lord, you have turned your backs upon me, and therefore have constrained me to deprive you of my grace. Do not oblige me to drive you forever from my face, and punish you in hell without hope of pardon. Have done with it: abandon sin, be converted to me, and I promise to pardon you all your offences, and once more to embrace you as my children.’
St. Alphonsus Maria de Liguori