At some point, we humans must admit that we are on the downhill side of life; the slide might be long and gradual or steep and short. Of course, due to disease, accidents or violence, some enter the slide much earlier than most; in all cases, we are forced to acknowledge that our future is much shorter than our past.
While a healthy lifestyle might delay the process, we all eventually recognize the symptoms: weaker muscles, less energy and a diminished appetite among many others. Some turn to a wide variety of supplements to slow aging but they are of dubious value; genetics and luck (good or bad) are the primary determinants.
Those of us who enter our seventies, eighties or beyond in decent health and still independent are very fortunate indeed. Then again, Mother Nature has the final say and she often arrives unannounced.