To be young again

There's a bittersweet ache in my heart
When I encounter the innocent joyousness of youth
The music they sing along to -
Was once mine
And the possibilities too.
I'm not old but I do feel -
The poignant aftertaste of life passing by.
Like a river whose flow
I cannot stem.
Then again, stationery, it wouldn't be the thing of feisty beauty
It now is.