Steps
1. When you smile naturally, your whole face moves. Fake smiles involve just the mouth, and people notice something wrong. The next time you are REALLY smiling, take note of the muscles in your cheeks, forehead, and temples. If you want to be able to consistently smile with all your face, you will have to identify and practice this, just as you did with the mouth alone.
2. Know that 80% of a sincere "smile with the eyes" is just getting the muscles of your face trained properly. However, there is one last step, the real "smiling with the eyes", and it can't be faked. When something really makes us happy, our eyes get brighter, taking on an excited shine or gleam. This is the exact opposite of "glassy eyes". In order to be able to do this on command, you will need to train your mind with practice, just as you trained your face. You have to learn to convince yourself that what you are smiling about is really something you like and are excited about. If you can't do this, you will have to practice quickly bringing to mind a memory or image that makes you happy. When you have to give your best smile (even if you don't feel happy), quickly think of this happy thought and make the smile you practiced. Anyone watching will see a person smiling with their whole face.
Examples