At 29, Taylor Swift has 32 Grammy nominations and 10 wins. She has seven hit albums, her concert tours break records and her estimated net worth in 2018 was a whopping $320 million.

Swift turns 30 this year (in December) and despite her success, she says her 20s have been filled with trials and tribulations. But Swift has learned from them.

One of the noteworthy things Swift has learned is about the perils of being too nice.

"Being sweet to everyone all the time can get you into a lot of trouble," she writes for Elle in an article called "30 Things I Learned Before 30." "While it may be born from having been raised to be a polite young lady, this can contribute to some of your life's worst regrets if someone takes advantage of this trait in you," she says.

"Grow a backbone, trust your gut, and know when to strike back," she writes. "Be like a snake — only bite if someone steps on you."

Swift also says she's learned that "it's good to mess up" and to learn from your mistakes.