Aging is a gradual, continuous process of natural change that begins in early adulthood. During early middle age, many bodily functions begin to gradually decline. People do not become old or elderly at any specific age. Traditionally, age 65 has been designated as the beginning of old age.
Besides, what affects the aging process?
The most notable exogenous factors influencing degree of aging were sun exposure and smoking. Other possibly contributory lifestyle factors include alcohol consumption, stress, diet, exercise, disease, and medication.