11 Our fatherly solicitude urges Us to implore of God, the Giver of all good gifts, not merely the spirit of prayer, but also that of holy penance for all the sons of the Church. And whilst We make this most earnest supplication, We exhort all and each one to the practice with equal fervour of both these virtues combined. Thus prayer fortifies the soul, makes it strong for noble endeavours, leads it up to divine things: penance enables us to overcome ourselves, especially our bodies - most inveterate enemies of reason and the evangelical law. And it is very clear that these virtues unite well with each other, assist each other mutually, and have the same object, namely, to detach man born for heaven from perishable objects, and to raise him up to heavenly commerce with God. On the other hand, the mind that is excited by passions and enervated by pleasure is insensible to the delights of heavenly things, and makes cold and neglectful prayers quite unworthy of being accepted by God. We have before Our eyes examples of the penance of holy men whose prayers and supplications were consequently most pleasing to God, and even obtained miracles. They governed and kept assiduously in subjection their minds and hearts and wills. They accepted with the greatest joy and humility the doctrines of Christ and the teachings of His Church. Their unique desire was to advance in the science of God; nor had their actions any other object than the increase of His glory. They restrained most severely their passions, treated their bodies rudely and harshly, abstaining from even permitted pleasures through love of virtue. And therefore most deservedly could they have said with the Apostle Paul, our conversation is in Heaven:(13) hence the potent efficacy of their prayers in appeasing and in supplicating the Divine Majesty. It is clear that not every one is obliged or able to attain to these heights; nevertheless, each one should correct his life and morals in his own measure in satisfaction to the Divine justice: for it is to those who have endured voluntary sufferings in this life that the reward of virtue is vouchsafed. Moreover, when in the mystical body of Christ, which is the Church, all the members are united and flourish, it results, according to St. Paul, that the joy or pain of one member is shared by all the rest, so that if one of the brethren in Christ is suffering in mind or body the others come to his help and succour him as far as in them lies. The members are solicitous in regard of each other, and if one member suffer all the members suffer in sympathy, and if one member rejoice all the others rejoice also. But you are the body of Christ, members of one body . (14) But in this illustration of charity, following the example of Christ, Who in the immensity of His love gave up His life to redeem us from sin, paying Himself the penalties incurred by others, in this is the great bond of perfection by which the faithful are closely united with the heavenly citizens and with God. Above all, acts of holy penance are so numerous and varied and extend over such a wide range, that each one may exercise them frequently with a cheerful and ready will without serious or painful effort.
Source: Octobri Mense (Vatican.va)