Answer:
Sometimes you feel it weigh a ton. Yet it is nothing, but somehow still there. Makes you uncomfortable around anyone, But speak its name and it's gone.
A standard dimension for sandwiches and rulers
They are two brothers. However much they run, they do not reach each other.
Who plays when he works and works when he plays?
What goes up and down the stairs without moving?
People take me on walks and I run and have fun. What am I?