The many things we failed to do, and now regret, are not wasted.  The hurts and injustices that have haunted us have value in what they produce to Christ’s yielded ones.  Sometimes we say, “I would like to go back and start over if I could know then what I know now’.  Truth is, all of those “regrettable” things are why we are where we are; these have gone into helping us know what we know now.  They all are pieces of character development.  The past is past.  I am what I am now by the grace of God.  Move on.  Shaping grace is still shaping you. 

“For I am the least of the apostles, and not fit to be called an apostle, because I persecuted the church of God. But by the grace of God I am what I am, and His grace toward me did not prove vain.” (1 Corinthians 15:9-10a NASB)