It is never too late to change! Well, there's nothing you can change about "the absolute rule of change being the only constant in your life".
Given the fact that lecturing, criticizing and punishing actually never promotes 'real change'!!! We have only one relief! If you'd like to see a certain behavioral change in your child's behavior, you have to check out the model, and that'll be you as the parent.
Once the model starts to change, the child will record (conscious or unconscious) the new much desired behavior... In due time the child will start demonstrating change, as well.
I know it sounds too simple but requires a lot of time and effort. Yet, growing up requires a lot of effort regardless of age! So as parents we keep on growing with our children!!!