Doesn't matter. Id imagine that killing another human being is never fun. There is a good chance that Zimmerman is living with the regret of killing Trayvon, no matter what kind of face he puts on.
Hell, there are cops who kill murderers and rapists, and who have trouble dealing with it. And the people they deal with it are vicious human beings.
And ya'll think it was so easy for Zimmerman to kill another human being.

I guess we all need heroes--we need to believe that there are badasses out there like Zimmerman. Zimmerman most likely cuddles his teddy bear to sleep every night.
I didn't follow the case, so I am unsure if this killing was justified. But what is quite obvious is that if cops and military people have trouble killing the "enemy," there is a good chance that your hero Zimmerman, is not dealing too well with it.