“ No one remembers who climbed Mount Everest the second time. ”
You don't have to be a hero to accomplish great things---to compete. You can just be an ordinary chap, sufficiently motivated to reach challenging goals.
~ Edmund Hillary
Good planning is important. I've also regarded a sense of humor as one of the most important things on a big expedition. When you're in a difficult or dangerous situation, or when you're depressed about the chances of success, someone who can make you laugh eases the tension.
I think it all comes down to motivation. If you really want to do something, you will work hard for it.
Nobody climbs mountains for scientific reasons. Science is used to raise money for the expeditions, but you really climb for the hell of it.