The typical hedonist today does not aspire to anything larger and higher, but settles for "feeling good". Such a life does not require fortitude. A truly meaningful life, is determined in regards to man's true end — which is the knowledge and love of God — does indeed require a host of virtues belonging to fortitude. The virtue of temperance is thus not enough for emotional well-being, since temperance deals with the greatest pleasures, not the greatest difficulties. Rather, it belongs to fortitude to remove the obstacles that withdraw the will from following reason on account of difficulties that give rise to fear and sorrow.
Catholics believe that the human person ought to love what is larger than himself, namely truth, justice, and the common good of the social whole. He ought to love the good of the entire civil community so much as to be willing to expose himself to the danger of death for its sake, and we would argue that he ought to love God (who is Truth) more than himself, and be willing to expose himself — not others — to the dangers of death for His sake, that is, for His cause.
St. Thomas writes:
Fortitude strengthens a man's mind against the greatest danger, which is that of death. Now fortitude is a virtue; and it is essential to virtue to tend to good; wherefore it is in order to pursue some good that man does not fly from the danger of death. But the dangers of death arising out of sickness, storms at sea, attacks from robbers, and the like, do not seem to come on a man through his pursuing some good. On the other hand, the dangers of death which occur in battle come to man directly on account of some good, because, to wit, he is defending the common good by a just fight. (ST. II-II.123, a. 5)
What does this have to do with sensuality and lust? Fortitude enables us to be strong in our use of reason when are passions threaten to enslave. The battle could be a military one, but more specifically the battle is always a "moral" one. For the sake of our salvation, for the love of others, for the establishment and strengthening of our wills, and for the good of the family unit we control our desires and appetites.
We love, so we do not let our selfishness hurt others. We choose the good because God is Good. Judges who refuse bribes, lawyers who refuse an unjust case, people who refuse revenge, a fireman running into a burning building, a parent giving up material goods and personal pampering for their child, all are using the virtue of fortitude.
Our strength, our fortitude is in the use of reason. It is not fearlessness, but the willingness to act in spite of fear or actual danger to ourselves. A person who lacks fortitude loves "external goods" and the goods of the body (temporal goods) more than his character, more than the common good, and more than the sovereign good, namely God. Thus, anything that he/she finds desirable must be had. If something is pleasurable to such a one, he can see no reason to avoid it. Excesses of self indulgence follow to the destruction of self and others.
It is also more than just will power. It is a process of using reason and making a decision. For Catholics it also means availing ourselves of the Grace of God and the power of the Holy Spirit through the Eucharist, other Sacraments, prayer and acts of charity.
We will still struggle against concupiscence and sensuality, but the struggle will not be hopeless. Be strong. Be fearless in the battle against sin. Be free.
Immaculate Heart of Mary, pray for us now and at the hour of our death. Amen