133 These exercises of piety have brought a wonderful increase in faith and supernatural life to the Church militant upon earth and they are reechoed to a certain extent by the Church triumphant in heaven which sings continually a hymn of praise to God and to the Lamb "who was slain." Wherefore, the Church not merely approves these pious practices, which in the course of centuries have spread everywhere throughout the world, but makes them her own, as it were, and by her authority commends them. They spring from the inspiration of the liturgy and if they are performed with due propriety and with faith and piety, as the liturgical rules of the Church require, they are undoubtedly of the very greatest assistance in living the life of the liturgy.
Source: Mediator Dei (Vatican.va)