If you're looking for the key to happiness — just ask Miley Cyrus!

Her older sister Brandi Cyrus is Miley's biggest fan, and she just revealed why the "Malibu" singer is so happy these days.

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"Something I really respect about Miley is that she really does truly know what's important and what matters. And that doesn't mean overworking herself and being on tour all year anymore," Brandi told E!. "That means her family and her life at home and her animals and making the music she really loves and I think that's something that comes with age when you start to realize that and she's there and that's why I think she's so happy."

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Miley's mom Tish Cyrus, who teamed up with Brandi for their new reality show Cyrus vs. Cyrus, also gushed about her newly sober daughter.

"I think Miley is so real and every stage you see her in is truly the stage of her life that she's in," she added. "She's in such a great place, so happy, and I think the music really reflects that."

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Miley, 24, recently opened up about this new stage in her life, including her relationship with Liam Hemsworth, and it's clear she's happier than ever.

“This record is a reflection of the fact that yes, I don’t give a f–k, but right now is not a time to not give a f–k about people,” she told Billboard. “I’m ­giving the world a hug and saying, ‘Hey, look. We’re good — I love you.’ And I hope you can say you love me back.”

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She continued, "I love talking to people, and I approach them in a normal, ‘Don’t treat me different, ’cause I’m not’ way. That’s what started this evolution for me."

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And when it comes to the Cyrus family, the feelings are mutual. Miley went on to wish Brandi a happy 30th birthday — and had some sweet words for the oldest Cyrus sibling.

"Happy B-Day @brandicyrus & congrats on your show launch! BIG day," she captioned an album of pics of the famous sisters at a basketball game. "Love you soooo much! PS as you slide thru these next few photos it will become very clear as to why I no longer drink! LOL! (Or maybe why I should start again…. J/K ) Always the best time when I am w my big sis! Xoxoxoxoxoxox."

She's just being Miley! For a look at all the Cyrus siblings, check out the gallery below!