I have to add my own two cents in here too. I think one more crippling behavior is that sometimes we "validate" our childrens' tendency to behave as "victims". When kids are mean to them at school, we teach them that those kids are mean and they should be nicer. We go to the principle, or talk to the teacher and behave as if it is others' responsibility to make our kids happy. But I'm wondering if this isn't a little bit backwards. We can't change the outside world...there will always be mean kids, or hard circumstances. Maybe we have to change our kids, to be able to be stronger inside: strong enough to handle hard times. They have to know that true happiness comes from within, and that they can be happy in spite of kids who are mean, or circumstances that are hard. We can strengthen our children and teach them coping skills. We can teach them how to find happiness in developing their talents, strengthening family relationships, or reaching out to other kids who might need a friend. That way they don't have to depend on others for happiness, and though they might feel bad that life is not exactly the way they would like it, they can still be happy.
I just think that we do our children a disservice by trying to smooth the way for them. Life will always be hard. So maybe the answer is that they need strength within, so they will always be up to the challenges life throws at them. And we need to teach them how to do it.