"When I was a 19-year old girl, [I] just moved to Los Angeles and I had this dream, like I knew exactly what I wanted to do," Perry tells us in the video above. "I guess I foreshadowed my future in some ways."
What she didn't anticipate, though, was her marriage to actor Russell Brand slowly falling apart during filming. With the cameras rolling, Perry can be seen uncontrollably backstage before a performance.
"If you were to have seen that movie without even a mention of it, you would be a bit confused, I think, and it would be silly and ignorant of me to think I could have completely avoided it."
Fans can get a full-on 3-D experience of the pop singer's highs and lows when "Katy Perry: Part of Me" hits theaters July 5.
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