I don't understand

I heard a story about one men. He said:

I got a message and a horse. I killed the horse and weren't able to deliver the message.

He was enthusiastic and eager but died young.

I was thinking and can't come to any conclusion. OK, you should care of yourself, but... BUT

BUT I think many people are just caring about saving that horse, not delivering the message

Sometimes I feel that I spend too much of my energy and there is nothing much left. But isn't that the only way that you can feel that you are really doing your best to deliver that message? I don't know. I am confused... :(