2 The patience of man, which is right and laudable and worthy of the name of virtue, is understood to be that by which we tolerate evil things with an even mind, that we may not with a mind uneven desert good things, through which we may arrive at better. Wherefore the impatient, while they will not suffer ills, effect not a deliverance from ills, but only the suffering of heavier ills. Whereas the patient who choose rather by not committing to bear, than by not bearing to commit, evil, both make lighter what through patience they suffer, and also escape worse ills in which through impatience they would be sunk. But those good things which are great and eternal they lose not, while to the evils which be temporal and brief they yield not: because “the sufferings of this present time are not worthy to be compared,” as the Apostle says, “with the future glory that shall be revealed in us.” And again he says, “This our temporal and light tribulation does in inconceivable manner work for us an eternal weight of glory.”
Source: On Patience (New Advent)