Reid Hoffman:

From this classic episode featuring Arianna Huffington:
http://listen.mastersofscale.com/XB8mN3G3
"If startups were easy, everyone would do it. They’re hard. But that hardness is the thing that gives you the chance to change the world.
All startups go through a valley of the shadow. All of them–PayPal, LinkedIn, things that I’ve done personally, things that I’ve invested in, Facebook, Airbnb–have valleys of the shadow, where you’re like, ‘Why did we think this was a good idea? We didn’t realize there was going to be this landmine, that it was going to be this hard.’
But that’s where you have the possibility of being heroic, of accomplishing something that no one else has done. Of making a change in the world that gets reflected in society and changes millions of people’s lives.
And that’s the reason why you face down these dark days, you band together, and you work very hard to solve them. And that’s your chance to be heroes.”