I mean, the homeschooling parent gives the kids something to do and tells the kid to go off and do it. With a good attitude. And proper motivation. And in a timely manner. I don't know about your little kids or what you yourself were like as a little kid but honestly, I just don't think it's going to happen. Mom's who sit around and wonder how to make it so are wasting their time.
I'm a Andrew Pudewa/ IEW groupie- have learned a lot from listening to his CD's and watching his DVD's on writing and classical ed. One thing that has really struck me this year is his comment to give kids help when they need it. This means that if your kid needs help with staying motivated then cheer them on as they are working. When the 7 year old can't work up the steam to tackle 30 problems on a written page, do the math orally. Be involved. It's taken me a couple of children to realize that "A word aptly spoken is like apples of gold in a setting of silver."
My advice to parents with kids who have motivation problems...Help them. They're asking for it in kidspeak. Attitude, motivation and behavior are the language of kids. Help them lot when they are little cause if you don't they sure won't ask you for help when they are big. And if they're big and need help, it's probably going to be about something that matters far more than addition facts.