From the CCC
2180 The precept of the Church specifies the law of the Lord more precisely: "On Sundays and other holy days of obligation the faithful are bound to participate in the Mass."117 "The precept of participating in the Mass is satisfied by assistance at a Mass which is celebrated anywhere in a Catholic rite either on the holy day or on the evening of the preceding day."118
2181 The Sunday Eucharist is the foundation and confirmation of all Christian practice. For this reason the faithful are obliged to participate in the Eucharist on days of obligation, unless excused for a serious reason (for example, illness, the care of infants) or dispensed by their own pastor.119 Those who deliberately fail in this obligation commit a grave sin.
**2184 **Just as God "rested on the seventh day from all his work which he had done,"121 human life has a rhythm of work and rest. The institution of the Lord’s Day helps everyone enjoy adequate rest and leisure to cultivate their familial, cultural, social, and religious lives.122
**2185 **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.123 Family needs or important social service can legitimately excuse from the obligation of Sunday rest. The faithful should see to it that legitimate excuses do not lead to habits prejudicial to religion, family life, and health.
**2188 **In respecting religious liberty and the common good of all, Christians should seek recognition of Sundays and the Church’s holy days as legal holidays. They have to give everyone a public example of prayer, respect, and joy and defend their traditions as a precious contribution to the spiritual life of society. If a country’s legislation or other reasons require work on Sunday, the day should nevertheless be lived as the day of our deliverance which lets us share in this “festal gathering,” this "assembly of the firstborn who are enrolled in heaven."125
I love my Catechism (-: