I think a lot of us have similar thoughts Meghan. We can all empathise with you which is a new experience for my emotionaly almost dead heart.
Concentrate on your breath. Listen and feel yourself breathing in, wait a few seconds, and do the same breathing out. If you find your mind wandering, come back to your breath again. You can't cancentrate on your breath and thoughts at the same time. This is mindfullness: adventures in the present moment. Everything else is in the past or future and are just thoughts.
An check out my resources for feeling better. There are some quick things you can do on there like counting backwards from 100 in sevens to take your mind of it.
M: 57 / EW: 52 T: 21, M: 8 S: 18, S: 15 Bomb: 1 Jun 14 EA Aug 2014 I think PA Feb 2015 possibly sooner