For some reason, youngness runs in my family. I have been rather down on myself the past year or two, but people do NOT believe me when I tell them my age, I have to show them my driver's license, and then their jaw drops from shock.
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BUt the amount of stress I have gone through the past 5 or more years, I feel like it has aged me .....maybe I just need a Hawaiin vacation or something, I dunno... 
Women age more than men usually because of having children. That is an enormously stressful and taxing bodily event that men cannot experience.
Other than that, aging is caused by:
--smoking
--sun exposure
--excess drinking
--substance use
--lack of sleep
--stress
Ok, well, STRESS, I've had alot of STRESS, that has GOT to be it.
I dont smoke, only have a glass of wine on occasion, dont abuse any substances and I sleep ok, for the most part, anyway.
Maybe I should go live in Hawaii for a year.