-by the virtue of the saving work of Christ accomplished once and for all. It follows that the sacrament is not formed by the righteousness of either the celebrant or the recipient, but by the power of God. From a moment that a sacrament is celebrated in accordance with the intention of the Church, the power of Christ and His Spirit acts in, and through it independently of the personal holiness of the minister.
Nevertheless, the fruit of the Sacrament also depend on the disposition of the one who receives them.

Explain if what your understanding about EX OPERE OPERATO is​