“Undoubtedly, as it seems to me at least, satiety of all pursuits causes satiety of life. Boyhood has certain pursuits: does youth yearn for them? Early youth has its pursuits: does the matured or so-called middle stage of life need them? Maturity, too, has such as are not even sought in old age, and finally, there are those suitable to old age. Therefore as the pleasures and pursuits of the earlier periods of life fall away, so also do those of old age; and when that happens man has his fill of life and the time is ripe for him to go.”

“Old age has its pleasures, which, though different, are not less than the pleasures of youth.”

W. Somerset Maugham book The Summing Up

“In short, enjoy the blessing of strength while you have it and do not bewail it when it is gone, unless, forsooth, you believe that youth must lament the loss of infancy, or early manhood the passing of youth. Life's race-course is fixed; Nature has only a single path and that path is run but once, and to each stage of existence has been allotted its own appropriate quality; so that the weakness of childhood, the impetuosity of youth, the seriousness of middle life, the maturity of old age—each bears some of Nature's fruit, which must be garnered in its own season.”
Denique isto bono utare, dum adsit, cum absit, ne requiras: nisi forte adulescentes pueritiam, paulum aetate progressi adulescentiam debent requirere. cursus est certus aetatis et una via naturae eaque simplex, suaque cuique parti aetatis tempestivitas est data, ut et infirmitas puerorum et ferocitas iuvenum et gravitas iam constantis aetatis et senectutis maturitas naturale quiddam habet, quod suo tempore percipi debeat.

Marcus Tullius Cicero (-106–-43 BC) Roman philosopher and statesman

“For to those who have not the means within themselves of a virtuous and happy life every age is burdensome; and, on the other hand, to those who seek all good from themselves nothing can seem evil that the laws of nature inevitably impose. To this class old age especially belongs, which all men wish to attain and yet reproach when attained; such is the inconsistency and perversity of Folly! They say that it stole upon them faster than they had expected. In the first place, who has forced them to form a mistaken judgement? For how much more rapidly does old age steal upon youth than youth upon childhood? And again, how much less burdensome would old age be to them if they were in their eight hundredth rather than in their eightieth year? In fact, no lapse of time, however long, once it had slipped away, could solace or soothe a foolish old age.”
Quibus enim nihil est in ipsis opis ad bene beateque vivendum, eis omnis aetas gravis est; qui autem omnia bona a se ipsi petunt, eis nihil potest malum videri quod naturae necessitas afferat. quo in genere est in primis senectus, quam ut adipiscantur omnes optant, eandem accusant adeptam; tanta est stultitiae inconstantia atque perversitas. obrepere aiunt eam citius quam putassent. primum quis coegit eos falsum putare? qui enim citius adulescentiae senectus quam pueritiae adulescentia obrepit? deinde qui minus gravis esset eis senectus, si octingentesimum annum agerent, quam si octogesimum? praeterita enim aetas quamvis longa, cum effluxisset, nulla consolatione permulcere posset stultam senectutem.

Marcus Tullius Cicero (-106–-43 BC) Roman philosopher and statesman

“May each of my grandsons know, at an early age, what his life's ambition is -- and may he be successful in his pursuit of that goal.”

Bette Davis (1908–1989) film and television actress from the United States

“Youth is the time of getting, middle age of improving, and old age of spending.”

Anne Bradstreet (1612–1672) Anglo-American poet

“Much reading after a certain age diverts the mind from its creative pursuits. Any man who reads too much and uses his own brain too little falls into lazy habits of thinking,”

Albert Einstein (1879–1955) German-born physicist and founder of the theory of relativity

“It is old age, rather than death, that is to be contrasted with life. Old age is life's parody, whereas death transforms life into a destiny: in a way it preserves it by giving it the absolute dimension. Death does away with time.”

Simone de Beauvoir (1908–1986) French writer, intellectual, existentialist philosopher, political activist, feminist, and social theorist

“Age is never so old as youth would measure it.”

Jack London book The Wit of Porportuk

“The pursuit of wealth generally diverts men of great talents and strong passions from the pursuit of power; and it frequently happens that a man does not undertake to direct the fortunes of the state until he has shown himself incompetent to conduct his own.”

Alexis De Tocqueville book Democracy in America