Betty, 66 years old, is in great physical shape. she works out at the gym every day, and recently her doctor told her she is in exceptionally good health. betty is young in terms of her age.

Betty, 66 years old, is in great physical shape. she works out at the gym every day, and recently her doctor told her she is in exceptionally good health. betty is young in terms of her biological age, it is the condition of our system, tissues and cells that marks our physical aging.