Jared Knighton and Taylor Clark study mormon scriptures at the Missionary Training Center of the Church of Jesus Christ of Latter-day Saints in Provo Tuesday June 18, 2013. Photo by Trent Nelson | The Salt Lake Tribune
(RNS) Mormon missions are often described as "the best two years." Many who serve talk about spiritual highs, miracles and mind-expanding experiences. Few detail how tough the work can be, how rigorous, how stressful.