Answer:
If you drop me I'm sure to crack. But give me a smile and I'll always smile back.
Where is the ocean deepest?
A king wears one on his head.
Longer than a decade and shorter than a milennium
I have joy in bringing two together, but darning my existence! My life hangs by a thread, filled with ups, downs and resistance!
People take me on walks and I run and have fun. What am I?