J.K. Rowling spent decades writing the Harry Potter series, the last book of which was published in 2007. And the author is still passionate about it — especially when it comes to how it's affected her young readers.

In the second part of her exclusive interview with TODAY's Matt Lauer, Rowling revealed that there's one thing that she's never tired of hearing: That her books have helped millions of children learn to love reading.

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"It's a wonderful thing to hear," Rowling told Lauer. "There are things I am bored of hearing. But it's certainly not, 'I really love your work and you taught my children to love books. What's better? That's an incredible thing to hear."

J.K. Rowling speaks with Matt Lauer on TODAY. TODAY

Another thing Rowling said she's proud of — her Harvard commencement speech in 2008. Titled, "The Fringe Benefits of Failure, and the Importance of Imagination." The speech earned more than 1 million views on YouTube and an illustrated version of the speech will be released as a book later this month.

"I don't think we talk about failure enough," she said. "It would've really helped to have someone who had had a measure of success come say to me, 'You will fail. That's inevitable. It's what you do with it.'"

Rowling said she was proud of the speech because it frightened her. "I'm normally proudest of myself after I've done something that frightens me because I, you know, believe in courage, and I think that it's the virtue that ensures all the others, as Winston Churchill said."

J.K. Rowling speaks with Matt Lauer on TODAY. TODAY

Rowling, who will celebrate her 50th birthday in July, said that she's looking forward to a party with her friends and family, and appreciating the time she has to raise her children and write more books.

"I really mean this and, not trying to bring the mood down, I promise. But my mother died at 45," she said. "From the heart, I mean this, you've gotta celebrate every year you're here in good health."