Alma 33:23

"And now, my brethren, I desire that ye shall plant this word in your hearts, and as it beginneth to swell even so nourish it by your faith. And behold, it will become a tree, springing up in you unto everlasting life. And then may God grant unto you that your burdens may be light, through the joy of his Son. And even all this can ye do if ye will. Amen."

When we accept the gospel of Jesus Christ in our hearts so many blessing come.  We can receive true joy through Christ and we can become pure.