Answer:
I tremble at each breath of air, and yet can heaviest burdens bear.
I am a good state, there can be no doubt of itΝΎ But those who are in, entirely are out of it.
How far will a blind dog walk into a forest?
Give it food and it will live, give it water and it will die.
You will find me with four legs, but no hair. People ride me for hours, but I don't go anywhere without needing to be tugged. Jerked or turned on, I always manage to be ready for work.
You use it between your head and your toes, the more it works the thinner it grows.