Too often, we are limited by our own limiting beliefs; or by what the rest of the world says is possible (or even factual). It's a good thing for society that some of us are not.
I'm reading a very interesting book (Get Out of Your Own Way, by Robert K. Cooper, PhD). In it, he made the following observation:
Robert H. Goddard, the driving force behind America's early space programs is today called "the father of space flight." But when Goddard first imagined that rocket could be propelled through out space, the New York Times ridiculed his dream, saying he lacked even "the knowledge ladled out in highschools." With no atmosphere in outer space and therefore nothing for an engine to thrust against, the Times patiently explained, a rocket couldn't move an inch.
What 'facts' are holding you back?