While not directly liturgical, lay devotion to the Eucharist, the Way of the Cross, and others have contributed to the liturgical calendar:
54. Just as notable a contribution to this progressive transformation was made by devotional trends and practices not directly related to the sacred liturgy, which began to appear, by God’s wonderful design, in later periods, and grew to be so popular. We may instance the spread and ever mounting ardor of devotion to the Blessed Eucharist, devotion to the most bitter passion of our Redeemer, devotion to the most Sacred Heart of Jesus, to the Virgin Mother of God and to her most chaste spouse.
From the earliest times of Christianity, devotion to saints has been part of our faith imagination. The tangible memories of their efforts: relics, places, and other aspects of their lives–these too have been part of the ritual expression of Catholicism:
55. Other manifestations of piety have also played their circumstantial part in this same liturgical development. Among them may be cited the public pilgrimages to the tombs of the martyrs prompted by motives of devotion, the special periods of fasting instituted for the same reason, and lastly, in this gracious city of Rome, the penitential recitation of the litanies during the “station” processions, in which even the Sovereign Pontiff frequently joined.
Not to forget the artistic expression of Christianity:
56. It is likewise easy to understand that the progress of the fine arts, those of architecture, painting and music above all, has exerted considerable influence on the choice and disposition of the various external features of the sacred liturgy.