For hundreds of years, no-one could beat the four-minute-mile barrier in track-in-field. It was said to be impossible. Until Roger Bannister made sports history...he refused to let that be a barrier in his mind...he did it...he broke the record. After that, hundreds of people were able to do it, too! What stopped other people from breaking this record for hundreds of years??? All of a sudden others were able to do what they couldn't do before. So, the lesson is...don't let your mind be a barrier. Don't let your dreams go by and let people tell you what you can't do.
I read about this in Chapter 4 of Joel Osteen's book, "Your Best Life Now...7 Steps to Living at Your Full Potential".