Causes of aging are few. Programmed organism slow-down caused by our internal cellular DNA changes. Environmental damages, caused by all kinds of environmental factors like UV radiation, cosmic background radiation etc. As with all other human characteristics, aging is individual.
Some people age faster than others. Aging process is tied to our habits. Food we eat, Places we live in. Water we drink. Stress we experience daily. Amount of love we poses and share with others. Sense of humour we have, All of this and more, affects our aging rate.