Joseph Smith only lived 38 years. He accomplished the translation of the Book of Mormon, the establishment of the Lord's kingdom, the establishment of cities and an army, and the foundation of a way of life for thousands of followers. He did all this in the span of only 15 years. He was able to accomplish this much because this was to be his sole endeavor, and because it was the work of the Lord. The Lord explained, in temporal labors thou shalt not have strength, for this is not thy calling (DC 24:9).