Why don't you look into anti-aging medicines or nutritional supplements?
I suppose it all depends on what you mean by 'natural'. For some this includes holistic remedies or alternative / complementary medicines.
All the obvious common sense things like regular exercise, balanced diet, plenty of anti-stress relaxation, good sleep - a healthy body and a healthy mind will all keep you feeling and most likely looking younger. Boost all of the above with an intake of nutritional supplements and good quality vitamins.
For an excellent range of anti-aging products check out antiagingcentral.com. What stricktlydating says is true except without sunshine we would all be Vitamin D deficient and definitely more miserable!