Rend your hearts.

     Here is an excerpt from Matthew Henry's comments on Joel 2:12,13.

     Our fasting and weeping are worth nothing if we do not with them turn to God as our God. When we are fully convinced that it is our duty and interest to keep in with Him, and are heartily sorry we have ever turned the back upon Him, and thereupon by a fixed resolution, make His glory our end, His will our rule, and His favour our felicity, then we return to the Lord our God.
     When the heart is rent for sin, and rent from it, then it is prepared to turn entirely to God, and be devoted entirely to Him, and He will have it all or none.