able to back up that saying. cnn's chief medical correspondent, dr. sanjay gupta, has the science behind feeling young. >> well, fred, i think for a long time, people have sort of guessed that there's a lot to this notion of how optimistic you are, how young you feel, and the impact that has on your overall health. but this is one of the first large studies to really put some definition around this. they followed around 6,500 people, the average age, kron logic age was 68.5 years. people who had the lowest self-piself self-perceived age, they were almost twice as likely to still be alive 8 years later as compared who had the oldest