What Am I Riddles

Question: While you were folding a letter I got you.
Usually you will do whatever it takes to avoid me,
but now you can't help but find me.

What am I?

Question: We are just like people. We grow, we get old, we die off. We come in many different colors. Black, white, brown. We come in a army, there are thousands of us, yet we have no war. But we will still die off over the years. What am I?

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: Men are just as small as stars to me but men can see me while the stars cannot. I am a reflection of the ocean and fire but never earth though without an earth you cannot have me.

Question: You bury me when I'm alive,
and dig me up only when I die.

What am I?