Yes, nice comforting lullaby. Never understood these types of texts.
“And time continues in its immemorial way of making everything and everybody look and feel like shit” – Martin Amis
This I understand. Sugar coating not necessary.
Well, but you see, there really are old people who (despite becoming frail and suffering pain) do not feel like shit.
Sure, there are many comforting lullabies offering a false hope (particularly religious ones), but this one doesn't strike me as one of those. (Remember that Russell was a staunch atheist, and did not tend to subscribe to false comforting beliefs.)
Just the opposite, it offers concrete advice, and embeds the process of getting older in a larger picture offering (secular) meaning.