Answer:
You use it between your head and your toes, the more it works the thinner it grows.
What looks back but cannot see?
I have four wings but cannot fly. I never laugh and never cry. On the same spot always found, toiling away with little sound.
Look into my face and I'm everybody. Scratch my back and I'm nobody.
What is the heart of many risks, has a heart, but is not a living being?
I can only be played on a windy day
Difficult
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?