That is why we should always study the word of God and have it dwelling richly in our heart, as St. Paul says (cf. Col. 3:16).
It is easy for grace to ignite one of these thoughts at the time of prayer, and then we have one verse from the Scriptures to pray with for a long time. And the Holy Spirit prays with us because this particular word is given by him.
This single thought that brings tears and repentance may come from the Holy Scriptures, quickened by grace; it may come directly from God Himself, through prayer; it may come from the hymnology of the Church, from a word of an elder or a brother; it can come from anywhere.
God is constantly seeking our heart, and He can provoke it with whatever is at hand. We only have to be ready to ‘snatch’ it.
Prayer of self-condemnation is especially helpful. The prayers before Holy Communion are full of these thoughts of self-condemnation before the thrice-Holy God.
I think that if we read them carefully we would always receive great help; one day one sentence from those prayers will stay with us and work repentance, another day another one, and so on.
Prayer of self-condemnation helps a lot because it follows the path of Christ, which goes downward. He is the One Who first went down, and He then ‘ascended up on high, he led captivity captive, and gave gifts unto men’ (Eph. 4:8).
For this reason Fr. Sophrony says that those who are led by the Holy Spirit never cease to blame themselves before God and this leads them downwards. But we must be careful, because not everybody can bear this.
Those who are healthy psychologically can do so and find great strength and consolation, but for those who are less strong, there is another way which involves giving thanks to God continuously and balancing the prayer by ending it with the words ‘although I am unworthy, O Lord’.
St. Maximus the Confessor says that true humility is to bear in mind that we have our being ‘on loan’ from God. We find humility if we thank God continuously for everything, if we thank Him for every single breath He gives us.
In one of the prayers before the Sacrament of Baptism, we say that God has spread out the air for us to breathe, and we find a similar idea in one of the prayers of the kneeling service at Pentecost.
Consequently if we thank God for everything and for every single breath of air that He gives us, we will maintain a humble spirit.