Your Darkness is Your Soul's Secret
To most people, you seem full of light and joy. You're the first one to smile or say something optimistic.
You put on a brave face for your friends, the family, and the world. You try to make the best of bad situations.
You keep your darkness a secret because you don't want to burden others with your problems. They have enough to handle as is.
You feel like your problems and struggles are for you to deal with. Everyone has them. What makes yours special?
If your darkness was less of a secret, people would be surprised to know what you've been struggling with... and that you're just like them.
You may burden others by revealing the darker parts of your soul, but you'd be unburdening yourself a lot more in return.