Good Riddles

Question: You struggle to regain me.
When I'm lost, you struggle to obtain me.
I pass no matter your will,
but I'm your slave to kill.
What am I?

Question: I wasn't born a horse,
and I never fly.
Yet sometimes I still soar,
right into the sky.
I often contain breath,
and yet I never die.
Sometimes I am torn,
but I never sigh.
Often, with ambition, I aspire,
and go till I can go no higher.
Then, like many men, so great,
I sink into a low state.
What am I?

Question: In spring I look gay, Covered in a green array, The warmer it gets the more clothing I wear, As the cold grows, I throw away my clothes.

What am I?

Question: Who was buried in Grant's Tomb?

Question: What can one not keep, two hold, and three destroy?