Potty Training Your Child

I can't really say I've potty trained a kid. Yet. I'm working on it. But I have attempted to potty train two toddlers. My own daughter, and a little boy I once nannied. So I can fairly say I've drawn some conclusions. I have gained something I've never had before: great respect for the people out there who have potty trained children. At this point, I'm surprised that there are so many adults out there who are able to take themselves to the bathroom. How do they manage to get from diapers to toilet? I am searching for the key, but haven't found it.