>> reporter: even the toughest are pushed to their limit. >> i always get asked, did you ever think about quitting? i have never spoke to anybody in the teams who said at one point they didn't at least think about it. the difference is, just like going into battle, controlling your fear. you don't quit. >> reporter: for months after hell week the training continues until these sailors become navy s.e.a.l.s. >> that sequence of developing confidence is part of s.e.a.l. training. >> reporter: ryan zinke was a s.e.a.l. team commander. >> that's why at the end, they're tough guys. when they go toe to toe against somebody there is an absolute belief that they will win. failure isn't an option and guys will not give up, ever. ever. >> reporter: that's why when the target is osama bin laden the president turns to the navy s.e.a.l.s and a special unit, s.e.a.l. team six.