Answer:
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
Don't do this in the shallow end.
What flies around all day but never goes anywhere?
My second is performed by my first, and it is thought a thief by the marks of my whole might be caught.
They made me a mouth, but didn't give me breath. Water gives me life, but the sun brings me death.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?