If the covenant ceremony at Mount Sinai can be compared to a wedding, then the Sabbath can be compared to a wonderful wedding gift. Wrapped up in blessing and holiness, it is a gift that continues to radiate the love of God every week.
The LORD commands Israel to remember the Sabbath. What does it mean to "remember" the Sabbath? Was there ever a danger of forgetting to keep the Sabbath? In Semitic culture, the word "remember" has clear covenant connotations. To remember means to act in faithfulness to the covenant. Similarly, God remembered Noah in the Ark, and He remembered Sarah when He was ready to open her womb. Therefore, God is telling Israel to show faithfulness to His covenant by keeping the Sabbath.
Rashi says that we should remember the Sabbath all week long by preparing for it. For example, he says that if a person comes across a nice article of food or drink during the week, he should set it aside for the Sabbath. This reminds me of a story from the days of the Master.
When the Master was not but a baby, there lived a sage by the name of Shammai. Whenever Shammai was in the market place, he always kept a lookout for exceptionally fine items that he might be able to purchase for the Sabbath. If he found a really good goat or chicken or vintage of wine, he would purchase it and say, "This is for the Shabbat." If later on in the week he found one even nicer, he would purchase that one for the Sabbath and use the previous thing he had bought on a week day instead.
Sometimes Gentile Christians want to keep the Sabbath, but they are distressed because in their current circumstances they cannot. They wonder what they should do.
If you find that you are unable to observe the Sabbath, you can at least remember it. At a minimum, this requires being conscious of the Sabbath's presence. Remember it on Friday night when the sun goes down and the Sabbath begins. Remember it on Saturday morning when the sun rises on the day of rest and the Torah is being read in the synagogue. Remember it on Saturday night as the holy day comes to an end. By doing at least that much, a person can take at least a small share in the Sabbath. The path of Torah is never all or nothing, and something is always better than nothing.