Answer:
Used left or right, I get to travel over cobblestone or gravel. Used up, I vie for sweet success, used down, I cause men great duress.
Die without me, never thank me. Walk right through me, never feel me. Always watching, never speaking. Always lurking, never seen.
My first master has four legs, my second master has two. My first I serve in life, my second I serve in death. Tough I am, yet soft beside. Against ladies cheeks I often reside.
Iron on a mammal. Mammal on your feet.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?
What language does a billboard speak?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?