And Abraham was old, and came into years: and Hashem blessed Abraham in all things (Gen 24:1).
All things - includes all age, for old age is a blessing.
Klei Yakor pioints out that for spiritually minded, old age with its attentuation of bodily drives and weakening of desires is a blessed time, a period of life when spirituality comes easier and there are fewer distractions.
This is the difference between Abraham and the nations. I recall a conversation years ago with elderly client who was complaining about the infirmities of old age. "But aren't you much wiser and more accomplished now?", I naively inquired. "I myself would not want to return back to those young and foolish years, with their ups and downs, their impetousness and emotionality, the needless suffering for reasons that were not real".
He looked at me without comprehension. Those were the best years of my life", he said "Wine, women and song! (he did not use exactly those words but something much cruder)".
Hashem blessed Avroham in all things, including his old age.
Another point about aging, here
Here is how R S. R. Hirsch expresses this idea (hat tip to hirhurim)
Here on the originally Quaker term Eldering and how it was co-opted by the Jewish Renewal Movement.

As a point on the other side, there is a chapter in Tzav V'Ziuz, by the Piaczena Rebbe, where he laments the humiliations of old age when a person hasn't worked to refine himself throughout his life. He had witnessed a very old man doing something repulsive and it really saddened him to see the low point a person could come to, even at that age, when he hasn't already worked to refine himself. It makes the point that this kind of old age can indeed be a blessed time, as you write about, for those who have been working all along to sanctify themselves.
-Dixie Yid
Posted by: Dixie Yid | November 24, 2008 at 10:19 AM
Yes, I recall seeing that in the English translation of this work. It's not quite the issue of infirmities but the absolute disgust at this old man seeking out sin despite being physically weakened to perform it. There was also an interesting discussion of why a person can be a tsaddik when young and then succumb to the lowest sins at an old age.
I think that Chazal hold the same.
Cf. Pesachim 113: The rabbis taught: .... The following four are unbearable: A poor man who is vain, a rich man who constantly tells lies, an old man who is lascivious, and a president of a congregation who considers himself superior to all others without cause.
A more relevant source is the dsicussion of Barzilai in Shabbat 152a and "Rav sighed when Rav Kahana read the passage from Job regarding the impotence of old age in front of him", ibid
Posted by: avakesh | November 24, 2008 at 01:15 PM