There is a famous instance of a holy man of old times, who, before his conversion, felt indeed the excellence of purity, but could not get himself to say more in prayer than ‘Give me chastity, but not yet.’
I will not be inconsiderate enough to make light of the power of temptation of any kind, nor will I presume to say that Almighty God will certainly shield a man from temptation for his wishing it; but whenever men complain, as they often do, of the arduousness of a high virtue, at least it were well that they should first ask themselves the question, whether they desire to have it. We hear much in this day of the impossibility of heavenly purity… are you sure that the impossibility which you insist upon does not lie, not in nature, but in the will? Let us but will, and our nature is changed ‘according to the power that worketh in us’… We dare not trust ourselves on the waters, though Christ bids us.
– Bl. John Henry Newman; What you are from not desiring a gift, this you make an excuse for not possessing it; P. S. V, 349-50