JOY is knowing that Jesus paid it all (our sins) at the cross.  All we can do is give God all the glory and honor- allowing Him to use the life we enjoy for His Glory!  Why not say to God, Here I am Lord, use me for Your glory! When you have this - called joy in your heart, you will have no reason to frawn and doubt, for worry not- God is in control, so relax my friend!