There are hearts of gilt,
And there are hearts of sin
There are hearts that lose,
And there are hearts that win.
There are hearts of stone.

But if my heart was anything,
It'd be a cactus.

Prickly and unwelcoming with tight alien-green skin,
That never fails to swell to accommodate whatever grew inside unseen.
With love it'd bulge,
And it'd shrink in the absence of love.

(But with the right care it could bloom the most spectacular flowers.)

There are strong hearts,
But even strong hearts give in.
My heart is a cactus heart,
My heart could keep it all in.