Answer:
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
It's got twists and turns, but has no curves. Twist it to fix it, turn it to ruin it. What is it?
What has 13 hearts but none beat?
It regulates our daily movements, but it feels no interest in our lives. It directs us when to come and go, but does not care if we pay attention. What is it?
What is so fragile that saying its name breaks it?
I appear in the morning. But am always there. You can never see me. Though I am everywhere. By night I am gone, though I sometimes never was. Nothing can defeat me. But I am easily gone.