A - Thanks for the question. You should be commended for caring about how you should observe a day of rest. Good for you! I know very few people who care to look up Canon Law, but be careful with it, because it is a foreign language for the uninitiated in parts of it.
Here is part of what the Catechism says about the Sabbath rest (it quotes Canon Law in part):
2184 Just as God "rested on the seventh day from all his work which he had done," human life has a rhythm of work and rest. The institution of the Lord's Day helps everyone enjoy adequate rest and leisure to cultivate their familial, cultural, social, and religious lives.
2185 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.
2186 Those Christians who have leisure should be mindful of their brethren who have the same needs and the same rights, yet cannot rest from work because of poverty and misery. Sunday is traditionally consecrated by Christian piety to good works and humble service of the sick, the infirm, and the elderly. Christians will also sanctify Sunday by devoting time and care to their families and relatives, often difficult to do on other days of the week. Sunday is a time for reflection, silence, cultivation of the mind, and meditation which furthers the growth of the Christian interior life.
2187 Sanctifying Sundays and holy days requires a common effort. Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord's Day. Traditional activities (sport, restaurants, etc.), and social necessities (public services, etc.), require some people to work on Sundays, but everyone should still take care to set aside sufficient time for leisure. With temperance and charity the faithful will see to it that they avoid the excesses and violence sometimes associated with popular leisure activities. In spite of economic constraints, public authorities should ensure citizens a time intended for rest and divine worship. Employers have a similar obligation toward their employees.
Second, we are to rest our bodies from the everyday labor. This means, if possible, we should not work. There are some who must and so they do nothing wrong in doing so. We wouldn't want a firefighter to let someone's house burn as part of a Sabbath rest.
Third, we rest our minds from the business of life. We should turn our minds toward God. This means an increase in our prayer and meditation. A spiritual book can be a nice addition to the day. This rest helps us properly order the good things in our life. Work is a gift and a good thing, but not in comparison to the highest good - God. We also remember that God is really the one doing (and already completed it) the hard work for us.
So, our rest should be one of the entire person. This will look different for every person. For instance, a student with a big final the next day might not look very restful one week, while the professor who already wrote the exam might not do much of anything the same Sunday. The point is to keep God in proper order and our lives as well.
What you do in your particular circumstances, I cannot say. But, remember the purpose of the sabbath -
"The sabbath was made for man, not man for the sabbath." Mark 2:27