I think everyone is well aware of Steve Jobs' story. Just want to quote the movie here.
"When you grow up you tend to get told the world is the way it is and you're life is just to live your life inside the world. Try not to bash into the walls too much. Try to have a nice family, have fun, save a little money.
That's a very limited life. Life can be much broader once you discover one simple fact: Everything around you that you call life was made up by people that were no smarter than you and you can change it, you can influence it, you can build your own things that other people can use."
"Here's to the crazy ones, the misfits, the rebels, the troublemakers, the round pegs in the square holes... the ones who see things differently -- they're not fond of rules... You can quote them, disagree with them, glorify or vilify them, but the only thing you can't do is ignore them because they change things... they push the human race forward, and while some may see them as the crazy ones, we see genius, because the ones who are crazy enough to think that they can change the world, are the ones who do."
Below is a video on a brainstorm session at early stage of NeXT. Pretty inspirational.