1 John 2:8 Yet I am writing you a new command; its truth is seen in him and in you, because the darkness is passing and the true light is already shining.
When we accept Christ into our lives, we do change, be it consciously or subconsciously. Whether we go the whole hog or just a little change is really up to us!
God would like us to be as much like Jesus as we can be, but our struggle with our old lives and the changes this brings in mean we do vary in how much we change.
Trust Christ to make the change as much as possible in you and help you to make it permanent – without Him it may well fail on the first day…