108 Many of the faithful are unable to use the Roman missal even though it is written in the vernacular; nor are all capable of understanding correctly the liturgical rites and formulas. So varied and diverse are men's talents and characters that it is impossible for all to be moved and attracted to the same extent by community prayers, hymns and liturgical services. Moreover, the needs and inclinations of all are not the same, nor are they always constant in the same individual. Who, then, would say, on account of such a prejudice, that all these Christians cannot participate in the Mass nor share its fruits? On the contrary, they can adopt some other method which proves easier for certain people; for instance, they can lovingly meditate on the mysteries of Jesus Christ or perform other exercises of piety or recite prayers which, though they differ from the sacred rites, are still essentially in harmony with them.
Source: Mediator Dei (Vatican.va)