I answer that, As stated above (FS, Question [31], Articles [3],4,5) where we were treating of the passions, pleasure is twofold; one is bodily, resulting from bodily contact, the other is spiritual, resulting from an apprehension of the soul. It is the latter which properly results from deeds of virtue, since in them we consider the good of reason. Now the principal act of fortitude is to endure, not only certain things that are unpleasant as apprehended by the soul---for instance, the loss of bodily life, which the virtuous man loves not only as a natural good, but also as being necessary for acts of virtue, and things connected with them---but also to endure things unpleasant in respect of bodily contact, such as wounds and blows. Hence the brave man, on one side, has something that affords him delight, namely as regards spiritual pleasure, in the act itself of virtue and the end thereof: while, on the other hand, he has cause for both spiritual sorrow, in the thought of losing his life, and for bodily pain. Hence we read (2 Macc. 6:30) that Eleazar said: "I suffer grievous pains in body: but in soul am well content to suffer these things because I fear Thee."
Now the sensible pain of the body makes one insensible to the spiritual delight of virtue, without the copious assistance of God's grace, which has more strength to raise the soul to the Divine things in which it delights, than bodily pains have to afflict it. Thus the Blessed Tiburtius, while walking barefoot on the burning coal, said that he felt as though he were walking on roses.
Yet the virtue of fortitude prevents the reason from being entirely overcome by bodily pain. And the delight of virtue overcomes spiritual sorrow, inasmuch as a man prefers the good of virtue to the life of the body and to whatever appertains thereto. Hence the Philosopher says (Ethic. ii, 3; iii, 9) that "it is not necessary for a brave man to delight so as to perceive his delight, but it suffices for him not to be sad."