WE MUST NOT content ourselves with being passively receptive to opportunities of acquiring virtue; rather we must actively seek them, embracing them with alacrity when found, and delight in those opportunities that bring the most mortification as they are the most advantageous. Nothing will appear difficult to us, with the assistance of Heaven, if we imprint deep in our hearts the following considerations.
The first is that opportunities actively sought are the proper, if not necessary means for acquiring virtue.

Consequently, as often as we beg from God any particular virtue, we simultaneously ask for those means which He appoints for its acquisition. Otherwise our prayer would be fruitless and contradictory; it would be tempting God, Who never bestows patience but through tribulation, nor humility but through ignominy.
The same may be said of all other virtues which are the fruits of those trials God wills to send us, and which we ought to cherish in proportion to their severity, as the violence we use in disciplining ourselves is of singular efficacy in forming habitual virtues in our souls.

Let us, therefore, be careful to mortify the will, if only in the repression of a curious glance or careless word. For although greater victories are more honorable, lesser victories are more frequent.

The second consideration, to which we have already adverted, is that we may derive advantage from all things inasmuch as they all are within the Providence of God. Indeed, properly speaking, things, such as the sins of men, cannot be said to happen by the wish of Him Who abhors iniquity; nevertheless, it is in some sense true, since He Who has the power to prevent, permits them.

As regards our own afflictions, whether they befall us through the fault of enemy or self, they are, nevertheless, in God's design, however displeasing the immediate cause may be, God expects us to bear them with patience, either because they are the means of our sanctification, or for reasons unknown to us.

If we are convinced, then, that perfect compliance with His holy will involves patient acceptance of those evils which the malice of others or our own sins draw upon us, how wrong, then, must they be, who, to camouflage their own impatience, assert that an infinitely just God can never be associated with that which proceeds from an evil cause.

It is obvious that their only aim is to preserve personal serenity, and persuade the world of their privilege to reject the crosses God is pleased to send. This, however, is not all; if the thing were indifferent on other accounts, yet the delight God takes in seeing our patient acceptance of injurious treatment-----particularly from those under obligation to us-----would be ample justification in itself for our practice of the virtue.

The first reason is that our innate pride is more effectively curbed by the ill-usage of others, than by any voluntary, self-imposed mortifications. Secondly, in suffering patiently such situations, we conform to the requirements of God, contributing to His glory; and we attune our wills to His in circumstances in which His goodness and power are equally made manifest. Hence from so vile a thing as sin, we gather the excellent fruits of virtue and sanctity. <>Know then, that God no sooner finds us resolved to attain solid virtue than He sends us trials of the severest kind. Convinced of His immense love for us and His fatherly solicitude for our spiritual advancement, we ought with gratitude to drink to the dregs of the chalice that He is pleased to offer us, confident that its beneficial character will be in proportion to its bitterness.

www.catholictradition.org/Classics/combat38.htm