The Sunday celebration of the Lord's Day and his Eucharist is at the heart of the Church's life." Sunday is the day on which the paschal mystery is celebrated in light of the apostolic tradition and is to be observed as the foremost holy day of obligation in the universal Church." Church law directs Catholics to their obligation to worship God on Sunday and Holy Days of Obligation by attending Mass. This follows from the fact that in the Mass it is Christ Himself who worships the Father, joining our worship to His. In no other way is it possible to adequately give thanks to God for the blessings of creation, redemption and our sanctification than by uniting our offerings to that of Jesus Christ Himself.

The following are Holy Days of Obligation as well as special solemnities or feast days in the 2022-2023 Liturgical Year:
 

"On Sundays and other holy days of obligation, the faithful are to refrain from engaging in work or activities that hinder the worship owed to God, the joy proper to the Lord's Day, the performance of the works of mercy, and the appropriate relaxation of mind and body." (CCC,2185)

Sunday is traditionally consecrated by Christian piety to good works and humble service of the sick, the infirm, and the elderly. Christians will also sanctify Sunday by devoting time and care to their families and relatives, often difficult to do on other days of the week. Sunday is a time for reflection, silence, cultivation of the mind, and meditation which furthers the growth of the Christian interior life." (CCC,2186)

"Sanctifying Sundays and holy days requires a common effort. Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord's Day." (CCC,2187)