We are given a break from physical drudge work so that we can attend to our soul and mind.
Sunday is the day to do things of culture -- art, sing, listen to music, poetry, writing, reading, dancing, having conversation, sports (especially with family), socializing -- things that make us cultured, sociable, normal human beings.
We are firstly supposed to do things that tend to help our SOUL (visit the sick, visit family, talk about the Faith, read spiritual works we normally wouldn't find time for, etc.). But it's equally OK to do things for the good of our MINDS -- such as the above list.
Basically, the liberal arts. Things that have no UTILITARIAN value -- philosophy, music, art, literature, history.
There is seldom time for such important human activities during the busy work week, when we are occupied with work, food, clothing, and shelter (caring for our BODIES).
In Christ,
Matthew