Tony Horton, the creator of P90X, was diagnosed with a rare neurological disorder. Now, he's fitter than ever at 66, thanks ...

Sales of the fitness videos, which have been around for more than a decade, really took off in August when Republican running mate Paul Ryan announced that P90X was his favorite exercise routine.

P90X trainer Tony Horton is in the best shape of his life at 66. Here are his top longevity tips.