And how can we suffer for Christ, you ask? If one accuse you falsely in any case, not on account of Christ, yet if you bear it patiently, if you give thanks, if you pray for him, all this you do for Christ. But if you curse him, if you utter discontent, if you attempt to revenge it, though you should not be able, it is not for Christ's sake; you suffer loss, and art deprived of your reward on account of your intention. For it rests with us either to profit, or to be injured, by afflictions. It depends not upon the nature of the affliction, but upon the disposition of our own minds. As, for instance, great were the sufferings of Job, yet he suffered with thankfulness; and he was justified, not because he suffered, but because in suffering he endured it thankfully. Another under the same sufferings, yet not the same, for none ever suffered like Job— but under lighter sufferings, exclaims, is impatient, curses the whole world, and complains against God. He is condemned and sentenced, not because he suffered, but because he blasphemed; and he blasphemed, not from any necessity arising from his afflictions, since if necessity arising from events were the cause, Job too must have blasphemed; but since he, who suffered more severely, did no such thing, it did not come to pass from this cause, but from the man's weakness of purpose. We want therefore strength of soul, and nothing will then appear grievous, but if our soul is weak, we find a grievance in everything.
According to our dispositions, all things become tolerable or intolerable. Let us strengthen our resolution, and we shall bear all things easily. The tree whose roots are fixed deep in the earth is not shaken by the utmost violence of the storm, but if it be set lightly in the surface of the ground, a slight gust of wind will tear it up from the roots. So it is with us; if our flesh be nailed down by the fear of God, nothing will be able to shake us; but if we merely intend well, a little shock will subvert and destroy us. Wherefore, I exhort, let us bear all with much cheerfulness, imitating the Prophet, who says, “My soul cleaves to You”; observe, he says not, draws near, but “cleaves to You”; and again, “My soul thirsts for You.” He said not merely “longs,” that he might by such words express the vehemence of his desire; and again, “Fix my flesh in Your fear.” For he wishes us so to cleave and be united to Him, that we may never be separated from Him. If thus we hold by God, if thus we rivet our thoughts upon Him, if we thirst with the love of Him, all that we desire will be ours, and we shall obtain the good things to come, in Jesus Christ our Lord, to whom with the Father and the Holy Ghost be glory, power, and honor, now and for ever. Amen.
Source: Homilies on Second Timothy (New Advent)