Even as you seek to take up your share of suffering for the sake of the Church, you must not romanticize the trials you face. To say "yes" to God and to the Cross does not mean you will be impervious to pain or never cry out to be spared. Crushed by the weight of the Cross or filled with fear over impending trials, there will be part of you that is overcome and wants to be spared; to cry out to God who seems to have forsaken or forgotten you. Yet, such a complaint can rise from the heart that still willingly accepts the suffering and accepts it lovingly as Our Lord Himself did when troubled in spirit and sweating blood in the Garden of Gethsemane. Beware, however, of a murmuring that is absent of such love and expresses not simply repugnance but revolt of the soul.
. . . we must distinguish the difference between complaining and murmuring. Complaining is in nowise an imperfection , it may even be a prayer. Look at our Lord Jesus, the Model of all holiness. Upon the Cross, did He not complain to His Father of being forsaken? But what is it that makes the difference between these two attitudes? Murmuring evidently implies opposition, malevolence (at least transitory) in the will; however, it proceeds more formally from the mind ; it is a sin of the mind derived from the spirit of resistance. It is a contentious manifestation. Complaint on the contrary, if we suppose it to be pure, comes only from the heart; it is the cry of a heart that is crushed, that feels suffering, but however accepts it entirely, and lovingly. We can feel the difficulties of obedience, experience even movements of repugnance: that may happen to the most perfect soul; there is no imperfection in this as long as the will does not adhere to these movements of revolt which sometimes get the better of the sensitive nature. Did not our Lord Himself feel such inward trouble? Coepit taedere et pavere et maestus esse. And what did He Who is our Ideal say in these terrible moments? Pater, si possibile est, transeat a me calix iste. “My Father, if it be possible, let this chalice pass from Me.” What a plaint wrung from God’s innermost Heart in the face of the most terrible obedience ever proposed here below! But likewise how this cry from the depths of crushed sensitive nature is covered by the cry, far deeper still, of entire abandonment to the divine will: Verumtamen fiat voluntas tua, non mea! From murmuring, on the contrary, love is absent: therefore murmuring separates from God; it destroys precisely what our holy Patriarch wishes to establish in us: that “amen” of every instant, that loving “fiat” coming more from the heart than the lips: in a word, that perpetual and incessant submission of our whole being to the divine will for love of Christ.
Marmion, Blessed Columba