Wang Xizhi (王羲之), from the 1rst link.
"The "Preface (Lantingji Xu)" to the poems is particularly famous in regard to the art of calligraphy."
https://en.m.wikipedia.org/wiki/Lantingji_Xu

This is a sad poem written about a phase of life that does not necessarily have to be so. Who knows what Wang Xizhi, the author's perspective was? Did he write the poem when he was already "old" and experiencing what he wrote about? Or did he see it in other people's lives? If the latter, did he envisage having similar experiences when he got old? What happened to you when you got old in ancient China?
If I should continue the questioning, what happens to old people in modern China? Is it different from what others experience in other parts of the world? By the way, what is old age? 100 years, 90, 80, ..........?!!!
Old age is a time of reflection of life lived, the experience of it all, the successes and failures, the joys and sorrows. It is also a time of self-judgement, the results of which contribute to the tone of your subsequent years on earth. The regrets and self castigation.
Old age is a time of increased vulnerability, not just to disease but to exploitation by others and harm. Humans are predatory; perceived "weaker" members are fair game! The vulnerability also has to do with the reduced ability to adapt to changing environments, specifically financial and professional/vocational. If you have not built up an adequate and resilient nest egg by then you may be forced to remain in the workplace for longer than planned, or rely on others for sustenance. You may not be as strong as you used to be and not very retrainable at work!
Yet, age is wisdom! There are many parts of the world where old age is respected and honored. Your experience of life is valued by all around you and your wise counsel is always sought for the purpose of avoiding pitfalls that confront the younger members of the family or societal unit. There are parts of the world where women become more respected as they get older and assume more communal authority and functions.
There are parts of the world where the inevitability of old age decline is not accepted. The mind set is different. The fact that you are getting older does not mean that any thing changes for you. Yes, you are getting older but you realize that "life continues" and nothing changes. Yes, you are getting slower but it does not mean that you are ready for the junkyard!
This is when you optimize your life and functions, understand your overall state of health and introduce interventions to protect and strengthen your physiological functions. This is when many begin to frequent the vitamins and minerals' aisle at the supermarkets, and start/maintain physical exercise regimens. Deliberate efforts at maintaining mental functions also occur at this time. If you are right handed you are told to use your left hand more often than before for example, soap yourself with your left hand! Do more crossword puzzles, try sudoku!
Yes, just as Wang Xizhi intoned, age comes at you fast. Our energy levels drop. The drive decreases. You get tired of fighting the same battles. You just want to throw in the towel. There may be circumstances beyond your control; you may be very sick and truly dependent on others for the rest of your life. If so accept it with grace but always maintain your dignity.
Life boils down to not giving up! You have to continue doing as much as you can. Chin up, enjoy life and don't give up. Life continues until the last breath!