Intrinsic or chronological aging is the natural aging process that you were born with. In other words, it's in your DNA & it is an inevitable process. Intrinsic aging is affected by free radical damage, hormonal shifts, and your body's inability to completely repair this damage.
Intrinsic aging is a continuous process that begins in your mid-20's, and will not be evident for decades. During your 20's, collagen and elastic production begins to slow down. The dead skin cells do not shed as quickly and your cell turnover decreases. Be aware that the cells, tissues and organs within your body age as well.
Extrinsic aging is influenced by your lifestyle choices and your environment. Bear-in-mind that this component to aging is in your control and it will magnify intrinsic aging, usually leading to premature aging.
Most premature aging results from sun exposure, repetitive facial expressions, gravity, sleep habits, over indulgence of sugar & alcohol, dietary choices, smoking, stress and pollution. Age associated changes include skin thinning, sagging, fragility, wrinkles, and pigmentation changes.
While you can't change your DNA's intrinsic aging process, you can influence and control the extrinsic aging component. Extrinsic aging speeds up your skin's natural aging process.