St. Paul writes about having received great revelations (cf. 2 Cor. 12:1-4). But God also permitted him to be struck by great trials, and one special trial constantly tormented him. It might have been an illness, a chronic physical ailment, which besides being particularly annoying, hindered his activity and gave him a clear understanding of his human limitations.
Paul repeatedly implored the Lord to free him from this suffering, until the reason for such a trial was revealed to him, that is, so that the power of God could be fully manifested in our weakness, for the sole purpose of leaving room for the power of Christ (cf. 2 Cor. 12:9).
This is why Paul could say:

«When I am weak, then I am strong.»

Human reason rebels against such a statement, because it sees it as an obvious contradiction or simply as a downright paradox. Instead, this phrase expresses one of the highest truths of the Christian faith. Jesus explains this with his life and especially with his death.
When did he fulfill the Work that the Father had entrusted to him? When did he redeem humanity? When did he win over sin? When he died on the cross, annihilated, after having cried out: “My God, my God, why have you forsaken me?” (Mt. 27:46; Mk. 15:34).
Jesus was the strongest precisely when he was the weakest.
Jesus could have given origin to the new people of God just by preaching, by working more miracles, or by performing some extraordinary deed.
Instead, no. No, because the Church is the work of God and it is in suffering and only in suffering that the works of God blossom.
Therefore, our weakness, the experience of our fragility conceals a unique opportunity, that of experiencing the power of Christ dead and risen and of affirming with Paul:

«When I am weak, then I am strong.»

We all have moments of weakness, frustration and discouragement. We must endure sufferings of every kind: difficulties, painful situations, illnesses, deaths, interior trials, misunderstandings, temptations, failures… What should we do? If we want to be consistent with Christianity and live it out radically, we must believe that those very moments are special ones.
Why? Because it is precisely when we feel incapable of overcoming certain trials which afflict the body and the soul – which means that we cannot rely on our own strength – that we are in the condition of trusting in God.
Then attracted by this confidence, he intervenes. And when he acts, he does great things, which stand out precisely because they are in contrast with our smallness.
In this light then, let us bless our smallness, our weakness, because it enables us to make room for God and to receive from him the strength to continue to “believe, hoping against hope” (cf. Rm. 4:18), and to love in a concrete way to the very end.
This is what happened to a couple in Switzerland whose son was dependent on drugs. They did not give up. They sought treatment for him everywhere, but it was in vain. One day he did not return home. They had feelings of guilt, fear, powerlessness, shame. But it was the encounter with a typical wound of our society in which they could see the countenance of Christ crucified and find new strength to continue hoping and loving.
Overcoming their utter weakness and powerlessness, the family members felt an inner energy never experienced before. They opened themselves to solidarity and organized a group of families who decided to do something about the situation. They brought sandwiches and tea to the young people of the Platzspitz, known at that time as the drug hell of Zurich. One day they found their son there, worn out and ragged. With the help of these other families, he was able to begin and successfully conclude a long journey to freedom.

Chiara Lubich