... time

They always take me for granted, but when in need, they wish a piece of me.

What am I?

Too  much time, not enough time, not now. STOP!

Time runs out and you can`t catch it.

It slips through your fingertips and you hope you could save it.

You spend it as if you could buy it right back.

And you realize you`re fighting a battle you can`t win.