Keeping Sunday Holy
Try the audio sermon linked above on Keeping Sunday Holy.
We are to avoid unnecessary servile work on Sundays. That includes mowing the lawn, and any unnecessary chores around the house.
Also shopping to be avoided unless necessary. You not only should not do it for your own sake, but for the sake of others, so that Sunday will become more of a day of rest for all people as it is meant to be – we give a bad example if we do otherwise, which is the sin of scandal, as well as the sin of not keeping Sunday properly, which can be of grave matter.
You can do recreational activities, including physically active ones, as long as they are truly this and not labor, i.e. tending the garden is actually labor, not recreation basically however enjoyable it may be – just because you love your work doesn’t mean it still isn’t basically work, and also a bad example to do. Landscapers get this day off too.
The day is meant for mass and peaceful reflection on the Lord, it should revolve around Him, and the spiritual rather than any physical labors.
Spiritual reading, walks, sitting out and admiring nature, playing a boardgame, etc.
Keep it peaceful. Keep it full of God.