Duff says during her time on "Lizzie McGuire," the show she starred in for two seasons that made her famous, she "got to do so many fun things and be so physical with my comedy. I had no inhibitions. It was fun for me to be goofy."
"Then I wanted to sing and that was new but I had so many fans by that point they were all supporting me so I was really confident. Now I'm a little older and I feel I need to re-learn some of those things. I have goals and aspirations but they kind of fall into what I've already accomplished. I feel like I still have work to do within things I've already dabbled in."
One recent success she's had is in the publishing world. Duff's a best-selling young adult novelist with her "Elixir" trilogy. The second book, "Devoted" is now in stores.
"To put a book out was huge," she said. "To hear people be like, `I didn't want to give you much credit but I love this book.' It's an overwhelming feeling of gratefulness and relief."
Besides writing, 24-year-old Duff is expecting her first child with pro hockey player Mike Comrie. The two married in 2010.
She says she sees fans posting on Twitter that her pregnancy makes them feel old.
"The truth is that I'm very young and things in my life have happened very fast. I guess, why stop now?"
She doesn't know if the baby is a boy or a girl, but plans to take her husband, mom and sister (actress Haylie Duff) to the appointment to find out. Duff says the suspense is "killing" her and predicts it will be a boy.
Although she's grown up in the spotlight Duff says being in the public eye can be hard while she's experiencing the ups and downs of pregnancy.
"Being pregnant every day is a little bit different. Sometimes you're feeling great and sometimes you just like could cry at the drop of a hat. I handle it as best as I can I think."