It is a bit bothersome and you can only receive it from someone else.

A dialogue in Naruto Shippuuden, episode 296 "A Father's Hope; A Mother's Love", between Gaara and his uncle Yashamaru:

Yashamaru: Physical wounds will definitely bleed and may look painful. But over time they heal by themselves. And if you apply medicine, they will heal faster. What's troublesome are wounds of the heart. Nothing is harder to heal. 

Gaara: Wounds of the heart?

Yashamaru: They are a bit different from physical injuries. You can't apply medicine, for one thing. And sometimes they never heal. There is only one cure for a wounded heart. It is a bit bothersome and you can only receive it from someone else.

Gaara: What is it?

Yashamaru: It's love.

Gaara: Love?

Yashamaru: Yes.

Gaara: How do I get it?!



--- No wonder I'm in tears with practically every episode.