Kristen Bell called a little girl with brain cancer as Anna from 'Frozen,' and her dad taped it all.

It was such a warmhearted thing to do.

A 6-year-old girl who is bravely fighting an incurable type of brain cancer just got a heartwarming pep talk ... from Frozen's Princess Anna of Arendelle.

It came in the form of a voice message on her dad's cell phone. But unlike most kids who get a "message from Anna," it wasn't a prerecorded tape or her mom doing a voice.

Photo by Amy/Flickr.

It was Anna's voice actress Kristen Bell, herself.

Photo by Michael Buckner/Getty Images.

According to Megan Daley at Entertainment Weekly:

"The actress left an adorable message in the voice of her Frozen character, Anna, for Avery Huffman, a 6-year-old who was recently diagnosed with diffuse intrinsic pontine glioma (DIPG) — an inoperable brain tumor — last month, according to Huffman's official CaringBridge page."

"Bell got into full character for the young fan, congratulating her on being such a "good girl" and "so brave" — and that Anna's sister (Queen Elsa) would love to make her an honorary princess."

It was an extraordinarily big-hearted thing for Bell to do for a little girl who really needed some good news.

It's hard enough just being six, never mind having to deal with doctors, surgeries, and radiation treatments on top of all of it.

But the moment where Avery realizes she's listening to the voice of the real Anna?

Awww! GIF by Brandon Huffman/YouTube.

My heart just ... well. No words, really. Bell taking the time to speak with Avery makes a sad situation just a little bit brighter.

Avery's friends and relatives have been raising money for her care, and as of July 24, 2015, they were only a few thousand dollars shy of their goal. Hopefully the video of Avery receiving Kristen's message helps spread the word so the family can get Avery the care she needs.

You can hear the whole adorable message from Kristen Bell/Anna and witness Avery's reaction here:

Original video from Brandon Huffman.