We do many things to honor the Sabbath feeling that they make the day holy. For instance, we prepare the finest foods, dress in our best clothes, light candles in beautiful candle holders, have guests ... on and on we look for ways to be sure that we "sanctify the day." Sanctify means "to make holy" and surely these things help us to have a wonderful day, and even help us to remember that the Sabbath is holy. But actually, Sabbath is holy whether we do anything about it or not.
When Hashem first created the Universe He used six days to complete it, then on the 7th day He "rested" from creating and, "G-d blessed the seventh day and sanctified it because on it He abstained from all His work…."[i]
This tells us that the day itself is holy, and it has been holy every since Hashem first created it. So what is our spiritual job on the Sabbath? Our job is to recognize the holiness that is inherent in the day. And what is holiness? Only G-d is holy. Whatever we call holy simply helps to remind us that G-d is present.
This means that besides having an enjoyable day of rest we are to take advantage of the holiness of the time and look to see G-d in our lives. G-d is everywhere at all times, but He reveals Himself more easily in certain places and at certain times. Have a holy Sabbath.
[i] Genesis 2:3