I've had similar experiences, I had absolutely no idea how to study and I went to a tough college and it kicked my butt. Some things I think might have helped me:
Consistant challenge:
If you're not consistantly put into a position of work hard or fail, you just never work hard. It can't be a one off thing. I don't think this would have worked early, because a child doesn't yet believe in themselves. Once you hit high school though, if a child has developed a strong sense of (I call it pride) perfectionism (in the healthy sense) they will work hard because they simply dont' want to fail.
A VARIETY of challenge:
One thing that sucked was that in HS I got good grades in everything, like 100% perfect in everything. As a result I never figured out what I liked. Try to find some AP or EC for your child to help them figure out what they actually enjoy (and therefore want to work hard for).
