Anyone from Portugal?

I’m trying to hunt down a song I heard in Lisboa.

It’s a classical duet between an old man and a young man. The old man sings something about how he envies youth, and the young man sings there’s only hardship in his own future and asks why the old man wants to go through that again.

Basically I’m looking for a translation of the lyrics. But I can’t find this song as I don’t remember the title. Don’t you hate it when you’ve got a really specific question none can answer? It’s driving me up the wall.

Obligato