... There isn’t a secret calendar showing weeks when you can skip [Mass] based on a flimsy excuse, and other weeks when you have to show no matter what. Likewise, there isn’t a cosmic attendance policy giving you so many unexcused absences and then you fail the course.Italics are mine and that's what's going into my quote journal.
You either can come, and therefore you must. Or you cannot come, and therefore, well, you cannot.
Much simpler than people fear. The Church is not out to get you. Well, okay, she is out to get you. But in a good way: She is out to get your soul into Heaven. And she knows that under ordinary circumstances, attending Mass on Sundays and Holy Days is what your soul needs. So go if you possibly can.
Those who would like more specifics on the why's and wherefore's may find it in the Catechism, beautifully stated as is the norm there.