A very powerful and effective teaching tool that can help shape and change behavior, positive reinforcement works by presenting a motivating item (reward) after the desired behavior is exhibited, making the behavior more likely to happen again.
Resilience can be taught or developed in children by skillful parenting. Children need to learn that things do not always turn out the way they would like, but they can benefit, even from difficulties.
Children of this age are incorporating parental values - whether 'taught' or 'caught'. If you have not taken time to determine what values you want your children to learn, do it now so you can be deliberate in your teaching.