Arabic poetry يا ليت الشباب يعود يوما، لأخبره بما فعل المشيب
If only youthness may come back a day, so I may (complain/unbosom my feelings to it/tell it/lament to it/open my heart so it may sympathise with me/feel what I am feeling) what the grayness (signifies being old) has done.'
I just want to note that it's so eloquent in Arabic and so colourful because youthness is (Shabab meaning the youth) and grayness is (Masheeb). There's a similarity in the way it is pronounced and written. Gives it an extra spice. Maybe as english speakers, you can't see it but in Arabic it's extremely colourful.
Any idiom, proverb or piece of poetry suchlike? It's said as a lamentation about what being old has done, limiting one's options & not being able to do and enjoy what one used to do in dint of ailment or inability. It may also be said as a yearning to something pleasurable that happened in the past & is now unreturnable.