Answer:
Kills the bad ones and the sad ones. Tightens to fit, so one size fits.
What can bring back the dead. Make us cry, make us laugh, make us young. Born in an instant yet lasts a life time?
I am black when I am clean and white when I am dirty?
What flies without wings? What passes all things? What mends all sorrow? What brings the morrow?
This is in a realm of true and in a realm false, but you experience me as you turn and toss.
People take me on walks and I run and have fun. What am I?