3) When they're old enough to read out loud
In addition to the "affirmations for preschoolers" have them read this out loud every night to you or to the mirror. Be sure to print it up in big print. This is an example for a child named Mary.
...deserve to be happy and healthy.
I like myself.
I love myself.
I am getting better every day.
I am well behaved.
I am good in school.
I am loved by God and my family no matter what.