I had a friend who was a sniper in the U.S. Marine Corps, and
believe me, it was hard getting into sniper school, hard passing
the school and a hard life afterward. Not only do you have to have
a lot of patience (maybe "a lot" is an understatement...), but you
have to deal with the idea of pulling the trigger and taking
another man's life. Not many people can deal and live with their
conscience.
Somehow, my USMC friend was able to overcome his own demons, but he
still doesn't like to talk about his past.
Best of luck to you, but it's not all the glitz and excitement
which you see in Hollywood movies.