Answer:
I'm simple for a few people, but hard for them to hear. I live inside of secrets and bring people's worst fears. What am I?
I have roots nobody sees. I am taller than trees. Up, up I go but I never grow. What am I?
I can swim but never get wet. I can run but never get tired. I follow you everywhere but never say a word. What am I?
When you take away the whole from me there is always some left.
Weight in my belly trees on my back nails in my ribs feet I do lack.
The answer I give is yes, but what I mean is no. What was the question?