"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."
The Catechism of the Catholic Church # 2180

"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. Those who deliberately fail in this obligation commit a grave sin."
The Catechism of the Catholic Church # 2181

"On Sundays and other holy days of obligation, the faithful are obliged to assist at Mass. They are also to abstain from such work or business that would inhibit the worship to be given to God, the joy proper to the Lord’s day, or the due relaxation of mind and body."
The 1983 Code of Canon Law # 1247

"It is primarily the duty of parents and of those who take their place, as it is the duty of the parish priest, to ensure that children who have reached the use of reason are properly prepared and, having made their sacramental confession, are nourished by this divine food as soon as possible. It is also the duty of the parish priest to see that children who have not reached the use of reason, or whom he has judged to be insufficiently disposed, do not come to holy communion."
The 1983 Code of Canon Law #914

The above four paragraphs are direct quotations as indicated. The first two are from the Catechism of the Catholic Church which is a wonderful gift to us and gives us a greater understanding of our Faith. Every Catholic home should have a copy of this great work.

We are all disciples of the Lord Jesus and try to follow his example. The Church clarifies and specifies what that means. Here she says we are obliged to participate in the Mass. To "assist" or "participate" in the Mass is much more than simply saying "go" to Mass.

The second paragraph tells us why the Church wants us to participate in the Mass. The Mass is the very foundation of everything we do as Christians. The Mass is the source of our good works and we bring them back to the Mass and offer them with Jesus to the Father for his praise and glory.

The Eucharist is so important to our spiritual growth that children who have reached the use of reason must be prepared as soon as possible for the Sacraments of Confession and Holy Communion. It is primarilly the duty of the parents to see that this is done.

Notice that we are excused from Mass for a "serious reason". Each Catholic must judge if his reason for missing Mass is sufficiently serious. Illness or distance could be an excuse. If I am sick enough to miss other activities or so far from the Church that it would take me something like forty-five minutes or more to get there, I could reasonably excuse myself.

Notice also that abstaining from work or business on Sunday no longer refers to "servile work" as it did in the Code of Canon Law before 1983. The new code does not make a difference between intellectual work and manual labor. It simply says we are to avoid work and business that would inhibit the worship of God or the joy and relaxation of the day. You must be the judge of that. In modern society many people must work on holy days and even on Sundays. This necessity would excuse them but usually they can find time for Mass.

If necessary work prevents you from getting to Mass for long periods of time you should seriously consider making some adjustments. The Mass is so focal to following Christ and so essential to our beliefs and so necessary to preserve our Faith that the Church demands that we participate each Sunday and holy day.