Observe the Sabbath day by keeping it Holy, as the Lord your God has commanded you. You have six days each week for your ordinary work, but the seventh day is a Sabbath day of rest dedicated to the Lord your God. Deutronomy 5:12-14a NLT
We do not rest on the Sabbath so we can work during the week, (rather) we work during the week so we can rest and refresh our souls on the Sabbath. And by not working on the Seventh Day, we are affirming that God created the world and, just as He ceased from work on the Seventh Day, so do we.
Celebrating the Sabbath is not just an act of obedience, it is an act of faith. It is trusting that God will empower you to accomplish all that he has called you to do in six days a week.
Finally, keeping the Sabbath is a witness to an increasingly godless world. We can have no idea the impact of our act of faith and obedience in the Providence of God.