You grow up and you watch movies like Rambo or Commando, and you think Special Forces guys are all huge. Most of these guys aren't.
I've known and am good friends with a few SEALS. Most of them in uniform or street clothes look like normal people. Of course, they're in incredible shape, and ridiculously well trained. The key to being a SEAL is you have to have a cast iron will, you have to have a drive and a desire that most people don't. You have to understand that your body can do so much more than your mind will lead you to believe. Have a 'not dead, can't quit' philosophy.
90% of the people who try to become SEALS fail. While I would love to be 19 again to try, I'm pretty confident that I'd be in that 90% that wouldn't have made it. I've worked out with a few, and they're just relentless. They keep going, like machines.
I have the upmost respect for SEAL Team members.