The Westminster Puritans asked in Question 60 of the Shorter Catechism:
How is the Sabbath to be sanctified?
They answer that they gave:
The Sabbath is to be sanctified by a holy resting all that day, even from such worldly employments and recreations as are lawful on other days; and spending the whole time in the public and private exercises of God's worship, except so much as is to be taken up in the works of necessity and mercy.
I should tell you that I have disagreement with the Westminster Puritans regarding this answer. If the question was asked in regards to the Mosaic or Sinaic covenant alone, then I would say that they answered correctly. But the question is asked of a Christian, and of Sunday, because the 59th question and answer declared the Sabbath day changed from the last day of the week to the first day of the week.
The truth is, at no time in the New testament, is the New Covenant Christian commanded to keep the Sabbath. In fact, Jesus defended his disciples when the Pharisees accused them of breaking Sabbath law when they picked grain to eat on the Sabbath. The Lord concluded his defense of his disciples when he said:
But I say to you that something greater than the temple is here. But if you had known what this means, ‘I DESIRE COMPASSION, AND NOT A SACRIFICE,’ you would not have condemned the innocent. (Matthew 12:6-7)
Sunday is not the Sabbath, nor has the Sabbath rest been changed to Sunday. Christians meet on Sunday and call the first day of the week the Lord’s day, because it is on the first day of the week that the Lord, Jesus Christ, rose bodily from the dead and appeared to his disciples.
I must, however, give a warning. While it is legal, within the law of Christ, for the Christian to work and recreate on the first day of the week, it should not lead to the habit of forsaking the Christian assembly. Believers need to regularly meet with believers, to encourage one another in following Jesus Christ. (cf. Heb. 10:25)
Your Servant for Jesus’ Sake