I suspect that, as humans, we naturally want "poker faces." We all want to be impossible to hurt. We don't want to admit that we're imperfect or vulnerable in any way.
For some of us, this translates to perfectionism. I have a friend who has spent hours writing "perfect" emails to friends and way too much time coming up with the perfect tweet. (Yes, you guessed it ... that person is me.)
For others, this poker face (or mask) shows itself as extreme insecurity. I know many people who struggle with shyness—not necessarily because they're naturally reserved but because they fear what people will think of their true selves.
C.S. Lewis countered this perfectionism in a famous quote, where he wrote:
"If you want to make sure of keeping it in intact, you must give your heart to no one, not even to an animal. Wrap it carefully round with hobbies and little ... luxuries; avoid all entanglements; lock it up safe in the casket or coffin of your selfishness. But in that casket—safe, dark, motionless, airless—it will change. It will not be broken; it will become unbreakable, impenetrable, irredeemable."
Keep your heart from other people, and you will slowly die inside.
But what about the root of insecurity and perfectionism? We may know it's wrong in theory, but how do we get rid of the heart of insecurity?
Know that God loves you. Yes, you might've seen that one coming, but that doesn't make it any less true. Ask God to help the truth permeate your being: He loves you. You. Though God is intent on changing all of us and "growing us up" in Christ, let this sink in: He loves you, just as you are. Even if you were to die right now and never "grow up in Him," He would still love you. Even if you never changed, you would be His love.
Ask God to humble you. This has been a huge blessing for me and has greatly helped me fight the areas of insecurity in my life. Living humbly means knowing that God is great and the rest of us are just His creatures. Being His is an incredible honor, but it also puts us in our place. It says that we are lowly and only knowing Him (NOT being popular, looking pretty, dressing nice, making funny jokes) will satisfy the hunger in our hearts.
Only when we understand this can we begin to lose our poker faces.