The number of people who are living to at least 100 years old in the U.S. has doubled over the past decade.
Many centenarians credit their longevity, at least in part, to their positive attitude.
Roslyn Menaker, 103, told The Guardian that "happiness, joy, appreciation … a positive outlook," are why she has lived so long.
Ruth Sweedler, 103, told CNBC Make It that she was always praised for her good attitude growing up.
"I think the effects of just being positive are overstated," he says.
Persons:
Roslyn Menaker, Ruth Sweedler, David Watson
Organizations:
Guardian, CNBC, University of Notre Dame
Locations:
U.S