Polar bear, I love your post. When I worry about motivation in my kids, I remind myself of my own situation. I was the uber driven Ivy Leaguer. I am happy and fulfilled and I have a career that is very meaningful to me, but I'm not setting the world on fire. My sister pretty much watched TV her entire youth. Mediocre grades, no extracurricular activities, partied a lot in college. She now has her own firm that is at the absolute top of her field internationally. She does speaking engagements, publishes books, sits on non-profit boards.
Ha! So much for being "most likely to succeed!" (though I sincerely believe that I too have succeeded!)