Answer:
Now I don't know but I'm gonna say how I believe it.
Explanation:
I believe the meaning of the phrase is about how snipers have to assassinate people, and so if they feel any remorse or any anxiety, they can fail. As a saying, I believe it would mean if you have to do something bad, or you have to kill something. If you have any regret or feel anxiety, you can and will crumple under the pain of what you did. Hope this helps.
