Courage is not having the strength to go on, it is going on when you don't have the strength. Industry and determination can do anything that genius and advantage can do and many things that they cannot.
Nothing in the world is worth having or worth doing unless it means effort, pain, difficulty… I have never in my life envied a human being who led an easy life. I have envied a great many people who led difficult lives and led them well.
I've come to embrace the notion that I haven't done enough in my life. I've come to confirm that one's title, even a title like president of the United States, says very little about how well one's life has been led. No matter how much you've done or how successful you've been, there's always more to do, always more to learn, and always more to achieve.