— Steve Jobs American entrepreneur and co-founder of Apple Inc. 1955 - 2011
Context: I'm convinced that about half of what separates the successful entrepreneurs from the non-successful ones is pure perseverance. It is so hard. You put so much of your life into this thing. There are such rough moments in time that I think most people give up. I don't blame them. Its really tough and it consumes your life. If you've got a family and you're in the early days of a company, I can't imagine how one could do it. I'm sure its been done but its rough. Its pretty much an eighteen hour day job, seven days a week for awhile. Unless you have a lot of passion about this, you're not going to survive. You're going to give it up. So you've got to have an idea, or a problem or a wrong that you want to right that you're passionate about otherwise you're not going to have the perseverance to stick it through. I think that's half the battle right there.
The Computerworld Smithsonian Awards Program Oral History Interview http://americanhistory.si.edu/comphist/sj1.html, Advice for Future Entrepreneurs (20 April 1995)