Don’t mix and match, keep it new
No one sews a piece of unshrunk cloth on an old garment. If he does, the patch tears away from it, the new from the old, and a worse tear is made. And no one puts new wine into old wineskins. If he does, the wine will burst the skins—and the wine is destroyed, and so are the skins. But new wine is for fresh wineskins.
You can’t add bits of your new nature that you received from Christ to your old nature. It may seem nice decoration for a while but when the challenges and temptations of life set in it can be ugly. I mean you will be forced to choose between being faithful and being a sinner to a greater degree inside your heart.
The old self is full of vices. It has unbelief, laziness, low self esteem, apathy and a tendency to sin. Your new self in Christ is courageous, creative, pure, confident and faithful to God. As you see that the old and new self are completely opposed to each other. They can’t coexist, one nature will try to overcome the other.
This is where you make a firm choice to put on the nature of Christ. Decide to be totally transformed into a new creation in Christ. Don’t negotiate with the old nature which is the flesh. Many people try to tame the flesh but then their flesh ends up taming them.
You don’t wanna come so close to Jesus and then fall away due to the flesh nature. For this you need to understand that the Bible tells us to crucify the flesh and all its lustful desires. Nothing is more effective against the flesh than crucifying it.
Since the new nature is not compatible with your old nature you need to leave the old nature. The new nature that you received from Christ is full of life and great potential. Don’t waste it! Make it a daily choice to walk in this new nature. Pray to Christ that you are more aware of your new nature and totally forsake the old nature.