I have to source back to what one of my friends from my EMT class said. He had been a first responder for quite a while before taking the EMT class.
"You have to realize, if they are calling 911, they are probably pretty sick to begin with. It gives you a sense of accomplishment when you learn someone made it because of something you did. But you must always remember they are extremely sick by the time they call 911, because the time that you do not remember this, it will eat you alive."
My FD's district has a population of probably less than 3,000 people. A good 75% of the calls are people that we personally know. We deal with the pain in our own ways. Two of our first responders are husband and wife, they talk to each other about it to deal with their pain. One of our EMTs has a punching bag that he takes the bad ones out on.
I personally find that keeping myself busy (I know it is alot easier to do on a volly, its more difficult for me when I work a part time for county EMS) when I am not on a call is best. I play guitar, computer games, this forum, school work, heck even memorizing random stuff outside of school (best part of a useless fact is never having to recall it for a test

) Keeping myself impossibly busy and smoothering myself in music 24/7 is my way.
As a group, our departments small EMS squad has grown really close to each other, and when we have problems coping we turn to each other and we find the support we need.