Entrepreneurs are notorious for their ability to press on with their ideas despite what other people tell them. Naysayers abound when innovators want to try things nobody has ever done. Fortunately, innovative entrepreneurs have persisted with their efforts and given us some of the modern luxuries we now take for granted.

The Wright brothers mimicked the birds. Henry Ford harnessed horse power. They are but two well-known examples of visionaries who propelled the 20th century forward. Other now-famous people stared down negativity and triumphed. Find out how four such business-savvy folks stuck it out in the face of adversity.

Clarence Birdseye knew inferior freezing methods led to bland-tasting reheated food, so he developed quick-freeze machinery to produce quality frozen food. Shoppers didn't believe. Birdseye went broke. He stuck with it, eventually overcame consumer skepticism and went on to set the industry standard. Read more here.

Television network executives weren't sure the viewing public would accept a sit-com with a Cuban leading man married to a feisty, American redhead. So Desi Arnaz and Lucille Ball produced the "I Love Lucy" pilot with their own money. Network execs said TV shows had to be produced in New York and with kinescopes. Lucy and Desi took a salary cut to produce the show in Hollywood on expensive film, but, as part of the deal, the couple kept rights to the show. At every turn, Lucy and Desi were a step ahead of the studios, revolutionizing television along the way. Read more here.

Fred Smith wrote a term paper based on an idea for reliable overnight delivery. His professor gave him a C because the idea wasn't feasible. Years later, many potential investors agreed with the professor, refusing to send capital Smith's way. The funds he did raise in 1971 and '72 were gone by '74, along with his investors. One catchy slogan and several million dollars of hard-won capital later, Federal Express was on its way to profitability and long-term success. Read more here.

Steve Jobs wanted to give everyone a computer at a time when nobody realized computers were necessary to have. He founded Apple to create home computers, experienced some early success, faltered in the consumer market with the expensive Macintosh, was ousted from the company he founded, dabbled in computer animated movies-Pixar ring a bell?-and was eventually asked to return to his first love, where he turned around Apple at a time when it was in trouble. Read more here.