Answer:
I never was but always will be. No one ever saw me but everyone knows I exist. I give people the motivation to better themselves every day. What am I?
What goes through a door but never goes in and never comes out?
I can be winding and I can be straight. I can be smooth and I can be rough. Sometimes both. I start out black but fade to brown. My favorite colors are yellow and white and I love stripes and dashed lines.
I am a shimmering field that reaches far. Yet I have no tracks and am crossed without paths.
I am easy to see, but no one likes looking at me. Without me, there would be no you. What am I?
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.