One Bread, One Body
"The Eucharist is 'the source and summit of the Christian life.' 'The othe sacraments, and indeed all ecclesiastical ministries and works of the apostolate, are bound up with the Eucharist and are oriented toward it. For in the blessed Eucharist is contained the whole spiritual good of the Church, namely Christ himself, our Pasch.'
In brief, 'the Eucharist is the sum and summary of our faith.' 'Our way of thinking is attuned to the Eucharist, and the Eucharist in turn confirms our way of thinking.'"
Catechism of the Catholic Church, 1324 & 1327
"We must therefore consider the Eucharist as:"The Church obliges the faithful to take part in the Divine Liturgy on Sundays and feast days and, prepared by the sacrament of Reconciliation, to receive the Eucharist at least once a year, if possible during the Easter season. But the Church strongly encourages the faithful to receive the holy Eucharist on Sundays and feast days, or more often still, even daily."
"To prepare for worthy reception of this sacrament, the faithful should observe the fast required in their Church. Bodily demeanor (gestures, clothing) out to convey the respect, solemnity, and joy of the moment when Christ becomes our guest."
Catechism of the Catholic Church, 1389 & 1387