AceShowbiz - Selena Gomez endured a "nightmare" process to complete her new album because her health struggles caused her to repeatedly go back to the drawing board.

"Rare" hits retailers on Friday (January 10), and the pop star admits its launch is a long time coming, because she initially thought she was ready to share the new material with fans two years ago.

However, the "Come and Get It" hitmaker found herself wanting to constantly revamp and update the songs she had recorded to reflect the things she was experiencing in her personal life, including her various health struggles, which led her to undergo a kidney transplant in 2017 as a result of her lupus battle, and seek professional help for her mental health.

In a new interview with Spotify, she said, "Honestly, this album was kind of a nightmare to deal with, but in the best way possible."

"I thought that I was so ready (to release the album) like, two years ago... I had collected all of these sessions, beautiful sessions, that I don't even remember half of them because it evolved each year."

"And then something would happen to me and it would be very drastic, so that it would take me somewhere else (creatively)."

Selena, 27, used the past year to focus on her personal wellbeing, and now she couldn't be more proud of her work on "Rare".

"Then all of a sudden I found this healing, and I saw something bigger than what I thought that I was," she shared. "And I think that also added (to) the whole end of the album."

"Rare" marks Selena's first album in five years, following 2015's "Revival".