As one of the comments said: "Seals arent even human, there something else, something superior to the rest of the race. They are half machine half death sytch. The attrition rate to become one is a mind f***. You have to be the perfect human to even make it close to being reviewed by the military. These guys have the most godly job on earth. Lots of respect."
http://youtu.be/Io0jLmlTT1E