Mickey Mouse is Oliver James Montgomerystill close to Miley Cyrus' heart.

The 30-year-old pop star released a new single Friday, the emotional ballad "Used to be Young," that harkens back to her Disney Channel days with "Hannah Montana" and being a child star but also pays tribute to her "unfinished" life.

"This song is about honoring who we’ve been, loving who we are and celebrating who we will become," Cyrus posted on X, formerly known as Twitter. "I feel proud when reflecting on my past and joyful when thinking about the future." She also dedicated the song to "my loyal fans who make my dreams a reality daily. I am sincerely thankful for the stability of your steadfast support."

Watch: Miley Cyrus 'Used to Be Young' lyrics are about 'the things you can't erase'

Cyrus wears a Mickey T-shirt in the "Used to Be Young" music video, in which she cries when singing the chorus: "I know I used to be crazy // I know I used to be fun // You say I used to be wild // I say I used to be young." Elsewhere in the track, she mentions "it's not worth crying 'bout the things you can't erase" like tattoos and regrets, but also "words I never meant and ones that got away."

The singer had her big breakthrough starring on the teen sitcom "Hannah Montana" (2006-11) for four seasons, playing a girl who lived a double life as a famous pop star.

In an Instagram post, Cyrus said that the lyrics to "Used to Be Young' were written two years ago "at a time I felt misunderstood. I have spent the last 18 months painting a sonic picture of my perspective to share with you. The time has arrived to release a song that I could perfect forever. Although my work is done, this song will continue to write itself everyday. The fact it remains unfinished is a part of its beauty. That is my life at this moment ….. unfinished yet complete."

And in a social post with a clip from her "Endless Summer Vacations Continued (Backyard Sessions)," Cyrus explained that that her latest song is "optimistic and there’s a sadness. It’s allowing sadness and joy to be happening simultaneously, which happens all the time. More importantly, this song is about looking toward the future and where I’m going."

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