Academy Award winner Natalie Portman delivered this year's graduation speech to Harvard's graduating class of 2015.

In her speech, she addressed the "power of over confidence" and the "obliviousness of youth," as noted by The Hollywood Reporter.

She told them, "You are here for a reason. Sometimes, your insecurities and your inexperience may lead you to embrace other people's expectations, standards or values, but you can harness that inexperience to carve out your own path."

She also revealed the self-doubt that she faced after she enrolled in the prestigious university, which happened after the release of "Star Wars: Episode 1." The Washington Post quoted Portman, "Today I feel much like I did when I came to Harvard Yard as a freshman in 1999. I felt like there had been some mistake, that I wasn't smart enough to be in this company, and that every time I opened my mouth I would have to prove that I wasn't just a dumb actress."

The Oscar-winning actress has already received numerous awards in her career, however, she admitted that she thought it was her celebrity status, not her intellectual capacity, that gave her the slot in the Ivy League school. She said, "I got in only because I was famous. This was how others saw me, it was how I saw myself."

The best piece of advice she shared with the graduating class, however, is how to face the reality outside the four corners of the University. She told them, "You can never be the best. The only thing you can be the best at is developing your own self. Make use of the fact that you don't doubt yourself too much right now. As we get older, we get more realistic, and that includes about our own abilities - or lack thereof. That realism does us no favors."

According to the Harvard Crimson, Portman, who graduated with a Psychology degree in 2003, became the first graduate to ever win a Best Actress Oscar award. One former professor and former dean of social sciences, Stephen M. Kosslyn, said about the actress, "It was very clear when she was a student that she is a very determined person and capable of focused effort over a sustained period. She is now demonstrating the results of that determination and focus."

True to Kosslyn's words, Portman is very successful in her film career, and has crossed from being an actress to being a director. Portman had her directorial debut at the Cannes Film Festival with "A Tale of Love and Darkness," and is working on another film called "Planetarium."

Check out the rest of Portman's graduation speech here: