7 Though indeed the welfare even of the body is then more providently consulted for if its temporal life and welfare be disregarded for righteousness' sake, and its pain or death most patiently for righteousness' sake endured. Since it is of the body's redemption which is to be in the end, that the Apostle speaks, where he says, “Even we ourselves groan within ourselves, waiting the adoption of sons, the redemption of our body.” Then he subjoins, “For in hope are we saved.
But hope which is seen is not hope: for what a man sees, why does he also hope for? But if what we see not we hope for, we do by patience wait for it.” When therefore any ills do torture us indeed, yet not extort from us ill works, not only is the soul possessed through patience; but even when through patience the body itself for a time is afflicted or lost, it is unto eternal stability and salvation resumed, and has through grief and death an inviolable health and happy immortality laid up for itself.
Whence the Lord Jesus exhorting his Martyrs to patience, has promised of the very body a future perfect entireness, without loss, I say not of any limb, but of a single hair. “Verily I say unto you,” says He, “a hair of your head shall not perish.” That so, because, as the Apostle says, “no man ever hated his own flesh,” a faithful man may more by patience than by impatience take vigilant care for the state of his flesh, and find amends for its present losses, how great soever they may be, in the inestimable gain of future incorruption.
Source: On Patience (New Advent)