According to Judaism, the course of life – of real life – is not seen as an ascent towards adulthood, and from then on only descent.
Rather, it is an uninterrupted journey "from strength to strength."
Starting out life as an amorphous, inchoate mass, a utensil that has not yet taken shape, man goes on to acquires a more complete form, which he keeps shaping constantly through much study and good deeds, along with a constant perfection of body and soul, by directing them towards the real aim of life.
Seeing life as a whole, all of whose parts are equally important, gives a very different evaluation of life.
Once man builds this ability to live the present, to live life as it is, without picturing imaginary ideals, he can live old age just as happily as the young adult, in the peak of his vigor.
For the inevitable physical changes of old age are usually accompanied with parallel spiritual changes, which give man the possibility not to feel these physical changes – emotionally – at all.
Thus, when one puts aside all those imaginary aspirations that cannot be fulfilled, one can draw and enjoy goodness from every point along the path of life, and live life itself.
–Rabbi Adin Steinsaltz
From as essay, "From Childhood to Old Age: the Inner Aspect of Education" by Rabbi Adin Steinsaltz