Answer:
Everyone has me, but nobody can lose me. What am I?
I have a mouth on my head and eat everything.
I start new then become old. Start clean but be one dirty. I usually start big then become little.
The Titanic is still here. What am I?
Weight in my belly, trees on my back, nails in my ribs, feet I do lack. What am I?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?