The resultant injunction to keep holy the sabbath day was enshrined in the Law, with clear and detailed limits to what one could do on that day.  The Law considers that no work of any sort can be done on that day, even what we nowadays would consider the simplest of voyages or food preparation, and such restrictions are fairly stringent.

What Jesus is doing in this gospel passage is returning to the concept of rest, of restoration, of spending time with God the loving Creator rather than staying with a simple refusal of labor or energy expenditure.  His "Son of Man" here is not simply a reference to himself, it is also a reference to the fact that each of us must choose our own way of meeting God and spending quality time with him.  We need to get beyond the simplistic restrictions of the Law, each of us, and recreate ourselves, restore ourselves --- be recreated, be restored by God.  We become masters of the sabbath instead of its slaves, receivers of the gift of the sabbath rather than its victims.

For each of us, in our post-modern culture, that sabbath will be different, but it will naturally include worshipping with our faith community, praying and praising, learning and sharing with our sisters and brothers.  This will usually include some travel to get to church, probably some food preparation, certainly not only what the Law permits.

Keeping holy the Lord's Day is not a simple matter of getting to Mass under pain of mortal sin and of doing no significant physical or mental labor, it is entering into that original loving care for creation given to Adam and Eve in mission from the Lord, walking with Him in innocence and trust.

Going further into this might lead to extending this sabbath into the week rather than compartmentalizing it, but that's another matter...