I was listening to our favorite dog trainer one day in a class or lecture and he made a profound observation. It was profound as it relates to dogs but even more profound when you think about the kingdom of God. He was working with some people in a shelter in another town. [Picture this in columns] They had bios/case studies for various and sundry dogs, the behaviors that needed to change, the prognosis, and the plan to change the behavior (that's the gist of it, anyway.)
His question to the shelter workers was this - if you tear off the bios/the case study column for each of the dogs and throw it away, will it affect the behavior, the prognosis or the plan to change the behavior that you want to change? The answer was no. His comment was that attaching blame for yesterday doesn't help you fix the problem today - it doesn't change anything. You still have to deal with a recurring behavior that you have to change in order to keep the dog. (Hopefully, you want to keep the dog.) You have to keep moving forward.
If we dwell on the past. It doesn't help us fix today. Yes, we learn from our mistakes. Creatures learn from their mistakes if they're going to survive. But they also move on because they have to survive. We apply it to our own lives and to the children in our care. You do what you have to do to keep moving forward. When learning something determines whether or not you survive, you keep working at it until you get it. If you're afraid, you let God coax you forward until each step, each encounter, gets easier than the one before.
We have to focus on reinforcing and rewarding the behaviors we need today to replace of the old ("old" as in old and destructive not just because they're old) and we have to do it one day at a time. Maybe that's a little of what being a "new creation" is all about. With dogs (and kids, too) praise for a job well done and for making good choices, hard choices - praise goes a long way towards reinforcing the constructive behavior you want.
You can take the idea way out of the realm of behaviorism - the power of patient encouragement and forgiveness helps people move on and grow into new people. God still works supernaturally. I've seen Him do it. Sometimes He changes us on the inside and it shows on the outside, other times changing the outside eventually changes the inside. God is at work, either way. We partner with Him, either way. We praise Him, either way. Why you have to deal with this or that isn't really relevant anymore. You just have to do it. You can call it behaviorism or anything you want to but in the end, both the process and the result look like love to me.