According to the Chinese medicine, everything in the Universe is governed by Yin and Yang. The world requires a balance of Yin and Yang in order to run smoothly. For example, daytime is considered the Yang and needs to be balanced by Yin or nighttime.
Likewise, men are considered Yang on this earth and women are considered Yin. This designation, however, does not mean men only have Yang and women only have Yin. Yang and Yin exist in both men and women, but Yang is stronger than Yin in men and the vice versa is true for the women (Yin is stronger than Yang in women).
As men get older, men will gradually lose their Yang. The lack of Yang makes them sleepier or lethargic.
On the other hand, women lose the Yin when they get older. However, as the Yin gets smaller, the relative level of Yang becomes bigger or stronger. As a result, women become more energetic when they get older.
How to get more Yang or Yin? To get more Yang, men need to continue to do outdoor exercise as they get older, while women might need herbal medicine to supplement their Yin.
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