Be Careful It's My Heart (Four Freshmen)

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.