Lou started out as a very skinny 6'5" kid from New York. He began working out as a way to overcome a disability that he suffered as a toddler when he lost his hearing due to an ear infection.
He basically stormed onto the bodybuilding scene as a 21-year-old prodigy, winning several Mr America and Mr Universe contests, then battling Arnold Schwarzenegger for the Mr Olympia in 1974 and 1975. He never beat Arnold.
Lou played a big part in the film Pumping Iron, which pitted him against Schwarzenegger in the 1975 Mr O. While a lot of the movie was theatrics, the documentary did bring the sport of bodybuilding into the limelight and gave it some much-needed exposure to the general public.
Ferrigno then went on to become the Incredible Hulk, starring Bill Bixby.
Lou has also been in quite a few movies, including Hercules and Sinbad, as well as playing a role in The King of Queens, playing himself.
He also made one appearance in The World's Strongest Man contest. He participated with fellow bodybuilder Franco Columbu and they both showed that bodybuilders weren't just about showy muscles; they were indeed very strong.
Lou, of course, has his own web site and does a strong mail order business.