"If you want to be a great entrepreneur, you’re going to have to burn your résumé and stop worrying about your reputation, because you’re probably going to go through long periods of people calling you stupid." -- Mark Pincus, founder of Zynga.
I love this quote from Mark's recent interview in The New York Times Magazine ("I Don't Think It's Rotting Their Brains," April 7, 2008). It captures so well the mindset you have to have to succeed as an entrepreneur. You are putting your ideas out there for others to judge. The public, businesses, and your investors are going to making their feelings known by voting with their dollars. Your friends and family are going to be telling you what they think.
But if you have the vision, the fire and the perseverance, you will probably overcome the odds and make it.
The interview is short and worth a read...