I had reason to look up the Enchiridion Indulgentiarum in the Vatican web site a few minutes ago - as one does! This is the document from the Apostolic Penitentiary which sets out the rules for gaining indulgences, and lists the acts that the faithful can perform to gain indulgences.
The website carries the fourth edition, whereas my printed version is the original first edition from 1968. There are four "general concessions" for a partial indulgence listed at the beginning of the fourth edition of the Enchiridion, only the first three of them appearing in the first edition. The "usual conditions" - sacramental Confession, performance of the action itself, receiving Holy Communion and prayer for the intentions of the Holy Father - also need to be met. One can easily underestimate the value of these "general concessions" in favour of the more specific indulgences granted for special occasions such as the Year of St Paul or participation in the World Youth Day, but they do encompass very much the spirit of the revision of indulgences after the Second Vatican Council. They aim to encourage the faithful in their living of the Christian life so that they strive to live it more richly and more deeply, for their own good, for the good the whole Church and for the good of the whole world.
My shaky translations of the "general concessions" from the Latin are:
(1) for the raising of the heart and mind to God during the day, by means of a pious invocation, even if the invocation is only mental and not spoken
(2) for an act of service towards someone in need, undertaken in a spirit of faith
(3) for abstaining from something that is licit and good, in a spirit of penitence
(4) for giving an open testimony of their faith, in the particular circumstances of their daily life.
Number (2) is interesting in terms of how we understand an act of charity undertaken by a Catholic voluntary service in comparison to state provided welfare. The "spirit of faith" gives a kind of value added, a something more, than just the provision of the service in an exclusively material sense.
Number (4) is an encouragement to what we would now term the "new evangelisation", and I was most interested to discover it.