As the title implies, that's what you'll need to be successful. Mark has a great post about the nature vs. nurture argument in regards to entrepreneurs which was triggered as a response to Vivek Wadhwa who thought otherwise. The short version is that Mark believes in nature whereas Vivek believes in nurture. Mark also posted on what makes a great entrepreneur so he laid out on the table the characteristics he believes are necessary to be successful as an entrepreneur. Fred Wilson also has his take on entrepreneurs being born and not made.
Well, I wanted to throw in some of my own comments from 10+ years observation as a VC. I definitely sway towards the nature argument as do Mark and Fred. Most successful entrepreneurs I've been in contact with simply have it. Same goes for VC's. You simply have many of the qualities as described in Mark's "Entrepreneur DNA" right from the start. For example, it's really tough to learn "competitiveness" or "willingness to take risk". Actually I'd argue it's impossible to "learn" these traits. Same goes for many of the other traits described by Mark. But I'm not going to beat a dead horse. There are plenty of arguments and comments in both Mark's and Fred's post.
What do I feel is missing in this whole discussion? Well, it's luck! I'm the first to admit that I worked my butt off to be where I am. Yet, I too am the first to admit I've been pretty darn lucky on many occasions. Sure, I was presented with opportunities which I took advantage of but no matter how hard I would of tried, I couldn't of forced many of these opportunities. They simply happened....dumb luck! I met someone, was in the right place, knew something someone else didn't and so forth. Same goes for many of the entrepreneurs whom I have worked with and gotten to know. They happened to be at the right place at the right time. So few companies are actually successful when backed by venture capital. The media obviously celebrates the home-runs and we all love to talk about them. All too often though companies fail. At least half of all VC backed companies implode and go bankrupt. This is the reality of the venture business. Can one prove that success is always sweat and tears or sometimes just dumb luck? No, not really possible to do this. Do you have to work your butt off to make it as an entrepreneur? Yes, it's extremely hard! Yet I would argue that any successful entrepreneur would argue that many times, luck simply swayed the equation in the entrepreneur's favor.