There are also three “general grants” of indulgence. They are discussed in detail here in the Enchiridion of Indulgences. In summary, they are as follows:
I. A partial indulgence is granted to the faithful who, in the performance of their duties and in bearing the trials of life, raise their mind with humble confidence to God, adding even if only mentally — some pious invocation.
This first grant is intended to serve as an incentive to the faithful to put into practice the commandment of Christ that “they must always pray and not lose heart” and at the same time as a reminder so to perform their respective duties as to preserve and strengthen their union with Christ.
II. A partial indulgence is granted to the faithful, who in a spirit of faith and mercy give of themselves or of their goods to serve their brothers in need.
This second grant is intended to serve as an incentive to the faithful to perform more frequent acts of charity and mercy, thus following the example and obeying the command of Christ Jesus.
However, not all works of charity are thus indulgenced, but only those which “serve their brothers in need,” in need, for example, of food or clothing for the body or of instruction or comfort for the soul.
III. A partial indulgence is granted to the faithful, who in a spirit of penance voluntarily deprive themselves of what is licit and pleasing to them.
This third grant is intended to move the faithful to bridle their passions and thus learn to bring their bodies into subjection and to conform themselves to Christ in his poverty and suffering.
But self-denial will be more precious, if it is united to charity, according to the teaching of St. Leo the Great: “Let us give to virtue what we refuse to self-indulgence. Let what we deny ourselves by fast — be the refreshment of the poor.”
We see that these indulgences can be obtained in a great variety of ways and at any time–hence, their designation as “general” indulgences. We also see that these indulgences are attached to works that we should constantly be carrying out in our lives as Catholics! Prayer, charity, penance–these are all fundamental to Catholic life. But the Church, in her wisdom, knows that we may not always carry out our most basic duties, or at least, not always mindfully or particularly piously. And so she has put these indulgences in place partly to exhort us and to help us be more mindful of even the fundamental things.