What Am I Riddles

Question: What goes back and forth constantly, but never in a straight line?

Question: I fall while I'm flying, but can't touch the ground. I'm beaten all day, yet don't make a sound. I try to leave when you keep hitting me, but you always manage to somehow get me. No matter what I do, I always find my way back to you. What could I possibly be?

Question: I am the beginning of sorrow, and the end of sickness. You can't express happiness without me, yet I'm in the midst of crosses. You may find me in the sun, but never in the evening. What am I?

Question: What can you touch but not see?

Question: Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.