From Institute Manual:

President James E. Faust (1920–2007) of the First Presidency said: “We acquire a testimony of the principles of the gospel by obediently trying to live them. Said the Savior, ‘If any man will do his will, he shall know of the doctrine’ [John 7:17]. A testimony of the efficacy of prayer comes through humble and sincere prayer. A testimony of tithing comes by paying tithing. … I testify that if you continue in the purposeful process of searching for and accepting spiritual light, truth, and knowledge, it will surely come. By going forward in faith, you will find that your faith will increase” (“Lord, I Believe; Help Thou Mine Unbelief,”Ensign or Liahona, Nov. 2003, 22).