I once watched a video on youtube about the founder of ebay, Pierre Omidyar. The video was called 'Advice to entrepreneurs'. Expecting he would talk about himself and how he became successful, I found his words surprising. HIs speech was simple and yet sensible. He said that if you have an idea, don't let anybody tell you that you can't do it. People will try to convice you that your idea is not worth developing, just surround yourself by people who love you and listen to you. I strongly recommend you to watch it, it is just a couple of minutes long.
In my opinion, the essential ingredient to be an entrepreneur is DETERMINATION and HARD WORK.