It's not treating your heart like a commodity, it's more treating your whole self as something that others won't automatically see the value in. And you have to do it because they don't. Every human is unique and of immeasurable value and all that, but also nobody is bothering checking everyone when looking for new people. So you have to put your best and most desirable qualities forward, make people interested enough to see more and so when they start to see your worse qualities they have better qualities to make them feel like you're still worth their interest.

If I'm out at a bar, dressed in something attractive, putting out some playful charm, engaging in interesting discussions, and generally being fun to be around, people are going to be thinking about me as a hot chick who they might be interested in. Alternatively, if I'm sitting in the corner, too awkward to talk much, overly focused on unpleasant topics, and kinda a slob, the fact that people deserve love isn't going to make anyone interested in giving it to me.