The brick walls are there for a reason. The brick walls are not there to keep us out; the brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop the people who don’t want it badly enough. They are there to stop the other people!
Don’t build a product and then try to sell it.
Rather, get to know what people want to buy and then build it.
There are only two times when a man shall feel invincible.
When he has won everything, and then when he has nothing to lose.