Anti-Aging Face Cream

I have never used any anti aging face face creams before. Now that I will be hitting the big 40 in another 3 years, maybe I should start getting a good brand of anti aging face cream, lest my face wrinkles and sag. My skin is still very much supple, flawless and smooth and I have to say that daily exercising has a part to play in having good skin. But how long can this last? I wonder if anti aging face creams can really prevent the skin from sagging, wrinkling and aging.