When you look at the accomplishments of accomplished people and you say, "Boy, that must have been really hard," you know, when you look at something that looks hard, that was probably easy. And conversely, when you look at something that looks easy, that was probably hard. And so you're never going to know which is which until you actually go and do it. So just go and do it, try it, learn from it. You'll fail at some things, that's a learning experience that you need so that you can take that on to the next experience. And don't let people who you may respect and who you believe know what they're talking about, don't let them tell you it can't be done, because often they will tell you it can't be done, and it's just because they don't have the courage to try.
Source: Academy of Achievement: Pierre Omidyar Interview: http://www.achievement.org/autodoc/page/omi0int-1