I believe that desire is the spark that leads to wonderful righteous attainments. Captain Moroni spoke of the importance of a spark in a letter to Pahoran; he said, “And I will come unto you, and if there be any among you that has a desire for  freedom, yea, if there be even a spark of freedom remaining, behold I will stir up insurrections among you, even until those who have desires to usurp power and authority shall become extinct” (Alma 60:27). Moroni knew with even a trace or hint of desire, great things can and will happen.
Desires of the heart are what the Lord works with to stimulate and motivate us to action, to increased testimony, to change, and to becoming. Alma said in his great discourse on faith, “But behold, if ye will awake and arouse your faculties, even to an experiment upon my words, and exercise a particle of faith, yea, even if ye can no more than desire to believe, let this desire work in you, even until ye believe in a manner that ye can give place for a portion of my words” (Alma 32:27).
I love to call this “the particle principle.” If you give God a particle of desire, He will greatly reward that small amount of desire. If you give God an ounce of labor, he gives you a pound of results. Of course, this doesn’t mean that you can sit back and wait for Him to do all the work.