I\'m here today, gone tomorrow,
Some get by with from me, that which they did borrow.
Some have even thought,
Me, they have bought.
I can move slow, or way to fast,
I cannot go back into the past.
Me, some do waste, others have me to kill,
I come and go at my own will.
Some often wonder where I went,
Others with you, me have spent.
Some have me to spare,
When your\'s is running out you, I do scare.
Some have said I do heal,
I do not care how you feel.
I\'ve been known to fly,
I can, do and will quickly pass you by.
I\'m more precious than gold,
As I pass, you I make grow old.
What am I?