Ahhh yes, the hardened heart. I believe that we have all been there at one point in time or another and found it hard to ask "now what?". Then I look to King David, who was said to be a man after God's own heart (now that's devoted!), yet during his walk in the highest peak of his life, he "hardens his heart" by comitting many terrible sins. Covetness, adultry, murder and the like. But the point is after he had done this these and came to his senses, he repented, lamented, and really worked hard to get back what once was. I don't think he ever made it back to that point, but I believe God did forgive him. Just like today, none of us no matter how hard we try "loves God with all our heart, mind, soul" yet when we try, ask for forgiveness for the short coming, and try again tomorrow (even with more success) He rojoices because we did not give up and stayed the path. The hardening part I believe is meant for people who truly deny God, use His Holy name in vain, and the like. Remember God knows the heart better than anyone, and even He can break the "hardening" if He wants, He did for me.
Go in His peace. His arms are wide open for you to come to Him now with this burden on your heart.