Answer:
Until I am measured, I am not known. Yet, how you miss me when I have flown. What Am I?
I'm not a bird, but I can fly through the sky. I'm not a river, but I'm full of water. What am I?
I plow and plow, but never sow. What am I?
I get paid to shoot people then blow them up.
I am a ship that can be made to ride the greatest waves. I am not built by objects, but built by minds. What am I?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?