Keep the Sabbath Day Holy
Our Sabbath-day behavior is a reflection of our commitment to honor and worship God. By keeping the Sabbath day holy, we show God our willingness to keep our covenants. Each Sabbath day we go to the Lord’s house to worship Him. While there we partake of the sacrament to remember Jesus Christ and His Atonement.We renew our covenants and show that we are willing to repent of our sins and mistakes.
On this day, we enjoy a rest from our labors. As we attend Church services and worship together, we strengthen each other. We are renewed by our association with friends and family. Our faith is strengthened as we study the scriptures and learn more
about the restored gospel.
When a community or nation grows careless in its Sabbath activities, its religious life decays and all aspects of life are negatively affected. The blessings associated with keeping the Sabbath day holy are lost.
We should refrain from shopping on the Sabbath and participating in other commercial and sporting activities that now commonly desecrate the Sabbath.
http://tinyurl.com/2tj67q
Unless, of course, you fall into the category outlined in the 1978 Ensign article, and are very good at "sporting activities", in which case you're allowed to do what you want.