I have read what the Code of Canon Law and Catechism of the Catholic Church says about work on Sunday (below).
Code of Canon Law Chapter 1 (1247) Sacred Times
On Sundays and other holy days of obligation, the faithful are obliged to participate in the Mass.
Moreover, they are to abstain from those works and aVairs which hinder the worship to be rendered to God, the joy proper to the Lord’s day, or the suitable relaxation of mind and body.
Catechism of the Catholic Church
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.
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.
I would say these are quite clear to me. What I am not full clear on is the definition of work. Is it whatever you do to make a living, that makes you money, or is any physical work not allowed either?
I remember hearing that it is frowned upon for somebody to be doing some physical work around the house on Sundays (e.g. painting the garden fence etc.) but for instance, it doesn’t seem frowned upon to wash the dishes after dinner, and that could also be considered work. How about exercising? Going to the gym. Would those be considered physical work on a Sunday that should be avoided.