be, stay, etc. young at heart

be young at heart

To behave in a way that is more youthful than one's age. Grandma is still so young at heart—I can't believe she's taking dance lessons at 90 years old!
See also: heart, young

stay young at heart

To behave in a way that is more youthful than one's age. I can't believe grandma's taking dance lessons at 90 years old—how does she stay so young at heart?
See also: heart, stay, young

be, stay, etc. young at ˈheart

(of an old person) still feel and behave like a young person: He says that the secret of living to 100 is to remain young at heart.
See also: heart, young