Lyrics:

Sweetheart of mine, I've sent you a valentine
Sweetheart of mine, it's more than a valentine
Be careful, it's my heart
It's not my watch you're holding, it's my heart
It's not the note I sent you that you quickly burned
It's not the book I lent you that you never returned
Remember it's my heart
The heart with which so willingly I part
It's yours to take to keep or break
But please, before you start
Be careful, it's my heart