How do *they* do it?

Something about firemen, the police, lifeguards, army and practically every man and woman who put their life on the line to save someone else just does not make sense to me. Even more so when that someone else is whom they bear no relation to or have no idea who they are.

How can they abandon all thoughts of their own lives, their own families, their dreams and aspirations and risk it all for a faceless person. How can they walk in every single day of their lives to work knowing it could be their last. How does one even begin to comprehend that sort of pressure and sacrifice.

But then maybe we are not meant to understand. It is beyond mortal comprehension. Maybe these are the gods we mortals should be praying and idolizing because every minute of every day they are all that stands between one of us and the far beyond.

I still don't get it. How do they do it?