The Word of Wisdom is a set of guidelines, from the Lord, to keep us as healthy and strong as possible so that we can be better servants in the Kingdom. It includes adequate rest, proper nutrition, and refraining from harmful elements.
A modern-day Prophet (yes, we need those because our challenges are unique to our time and, just like all things, we need unique answers for those challenges) taught that "The Word of Wisdom leads to clean habits, thoughts, and actions. It will make you more receptive to the Spirit of God which cannot dwell in an unclean tabernacle.....(the gospel plan)...provides for solid work, clean entertainment, and activity to promote growth of stature." Benson, So Shall Ye Reap