From a Wall Street Journal review by Ellen Gamerman of the book by Becca Levy titled “Breaking the Age Code: How Your Beliefs About Aging Determine How Long & How Well You Live”:

Want to live an extra seven years? Think nice things about old people.

A new book on the psychology of aging argues that positive beliefs about growing old can add an average seven-and-a-half years to a person’s lifespan. Such good thoughts give the mind greater power over longevity than steps like lowering blood pressure (which adds roughly four years, according to the book), cutting cholesterol (four years), quitting smoking (three years) or losing weight (one year).