Lyrics: Irving Berlin. Be Careful, It's My Heart.

Be careful, it's my heart
It's not my watch you're holding, it's my heart
It's not the note that I sent you that you quickly burned
It's not the book I lent you that you'll never return

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