Heard this on the radio, and my life is changed!
How often as parents do we tell kids to do something, especially complex things, give them a string of orders, forget about it (for hours/days/weeks) and don't "inspect" until it's time to walk out the door/turn that project in/present something/etc.
Kids are not just little adults. A lot is going on and developing within their minds and bodies. Training is a continual process. You can try to force or beat a child to conform, but they will likely end up with all of the issues you have, if not some new ones.
My goal for my children is not for them to be conforming and obedient scarred adults. I want them to be healthy (mentally/physically/spiritually) and well-adjusted adults that know how to have healthy relationships. Most importantly, I want them to know and love God.
It's important sometimes to step back and try to see things from their perspective. How many of your child's issues stem from how you parent? Make your expectations clear. Reinforce them often. Show them and help them do whatever it is you have asked of them, if you see they are struggling.
Lessons for my self. I gotsta do better.