Anxiety.  

Anxiety is not a friend you want at your door giving you a high five and is excited to spend the night.
Anxiety is that skin scratching, pencil tapping, binge eating friend that appears like snow on a summer day.  
It comes out of nowhere. And sometimes you know you're about to start breathing heavily and wanting to lie down.
It's the feeling you get
when the love of your life says "Can we talk?"
when you lay in bed and you hear sounds
when you're in the hospital room and someone comes out with tears in their eyes towards you.
Anxiety is not that Christmas present you've been wanting all year...