Steve knew that others looked at him differently now; it took a little bit of the mystique out of Captain America when you realized that before he was Captain America he actually had been a 90 pound asthmatic weakling. But Steve had never seen himself that way.
He didn't hesitate to volunteer. If the world was at stake, he had a responsibility to defend it. "Captain America, the first Avenger" he said, and was transported to an entirely differently New York alongside his teammates, This didn't seem to phase him as much as it did them, but that was only because he'd wound up in an entirely different New York before.
"They're not alive," Cap was quick to remind his teammates. "They're already dead, and they're not real. They're not your friends; they're not your family. They're pawns in Mojo's game. They're the enemy that are keeping us trapped in here. The people that we care about aren't down there. They're outside of all this... counting on us not to fall for it. Remember that when this gets tough."