Word of Wisdom

“In the early days of the Church the Lord declared to the Prophet Joseph Smith "that all things unto me are spiritual, and not at any time have I given unto you a law which was temporal. . . . for my commandments are spiritual."
In harmony with this basic statement, the final and most important effect of the Word of Wisdom must be of a spiritual nature. Whoever obeys this law will be blessed in body, purse and mind, and also in spiritual development.
This is really self-evident. Obedience to the Word of Wisdom means eagerness and willingness to conform to the "word and will" of God, the beginning of all wisdom. It also implies conquest of the appetites of the body, the first step towards spiritual development.
…Those who, because of their acceptance and use of the Word of Wisdom, possess a clean body, a clear mind and a spirit in tune with the infinite, are best able to assist in establishing the Kingdom of God on earth, and thereby to render greatest service to their fellow men.”
John A. Widtsoe, Word of Wisdom: A Modern Interpretation