You are a child of God. No matter what mistakes you've made, no matter how worthless you feel, or how angry you are, or how bored and lost and bewildered life is making you. You are a child of Heavenly Father, and HE LOVES YOU. That is the first and most important thing.
As a child of God, you have an incredible birthright and potential. You have been given gifts, and God expects you to use them. You are intelligent, creative, and kind. You are patient. You are a selfless mother, a tireless father. You are a loving daughter or valiant son. You are a brother or sister. You can change the world.
This is not just fluff. You have the potential to inherit the kingdom of God and do things beyond your imagination. And if you look around you, all the people around you are children too. They are your brothers and sisters.
You have a capacity for love and grace, and your smile is one of the best things about you. Don't ever give up. Your Heavenly Father loves you.