Muhammad Ali

As an astronaut, when you're getting ready to go out of that hatch, you know that's the pinnacle of both your career and your life. The view completely blows you away. The real challenge is getting past the excitement and getting focused and down to work.

Some of the most inspiring moments in sports have come from players with physical defects. Tom Dempsey, born without toes on his right foot, kicked a 63-yard field goal in 1970, using a straighter, wider shoe.