By the final stanza we notice that the speaker suddenly sounds older, as if she somehow grew really old in the matter of the space between two stanzas.
Weird? Not really, because older folks do this kind of stuff all the time when they're telling stories. First they take us back to "when I was a young girl" and then after the memory is finished, they zip back to real time, which usually finds them rocking in a chair. Sometimes knitting is involved.
Though we don't necessarily see a rocking chair, we get the feeling that the speaker is definitely an older person trying to impart her wisdom to us.
And what's the moral of the story? Think about the good times kiddo, because in the end they're all we really have, especially when times are tough. After all, we don't want to end up in the grave worrying about all of the bills we didn't pay, right? Better to think about those good times and all the fun and love we were lucky enough to have. Nice and simple.