When a Christian takes the leap of faith and turns their life over to God, accepting Jesus as their mediator for sin, that's when true repentance starts. I believe it's the natural outcome of accepting the price Jesus paid for us. At least it was for me. Before coming to Christ I didn't need repentance...or at least didn't think I did. Now I realize I could live a thousand lifetimes and still not make ammends to God for what he gave to me through Jesus.