Answer:
It regulates our daily movements, but it feels no interest in our lives. It directs us when to come and go, but does not care if we pay attention. What is it?
Three little letters, a paradox to some. The worse that it is, the better it becomes.
What goes in the water red, and comes out black?
What has 4 legs in the morning, 2 legs in the evening and 3 legs in the night?
I am two-faced but bear only one. I have no legs but travel widely. Men spill much blood over me. Kings leave their imprint on me. I have greatest power when given away, yet lust for me keeps me locked away.
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?