In the last four years, Grammy winner Megan Trainor went from a shy body-conscious teen to a renowned pop star and body-positive activist.

Having low self-esteem and a belief that her looks and shape wouldn't allow her to become a star, Trainor had no expectations in 2014 during the release of her single, "All About That Bass".

So, it's no surprise that her mega-success left her stunned.

The Massachusetts native was raised in a music loving family. Her father, Gary was an organist for the United Methodist Church in Nantucket where the young Trainor regularly performed. The 22-year old's father told CBS in a recent interview that he was aware of his daughter's talents as early as age seven.

In her teenage years, Trainor's insecurities left her immersed in fear she would never achieve her dream of becoming a pop star. Instead, the young artist opted to stay behind the scenes and landed a publishing deal writing songs for other artists, including Rascal Flats.

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Two years ago when record executive L.A. Reid heard her new song, "All About That Bass," he got in contact with the young artist and immediately signed the soon-to-be star.

When asked if her empowering hit for full-figured females was a put-down of thin women, Trainor was matter of fact. "I didn't bash skinny people. I was just, writing for myself." By writing for herself the artist unintentionally wrote the words full of courage and self-esteem that many young women needed.

The Nauset Regional High School graduate recently revisited her hometown high school to sing her hit and talk to young people who might be struggling with similar issues.

With it's catchy tune and empowering lyrics, "All About That Bass" has left millions singing Trainor's words of self love. She told CBS, "I get messages all the time. ‘I hated myself, I didn't want to go to school. I was so uncomfortable, and now I love myself. I was in a really dark place until your song came out.'"

Trainor says that after that kind of response she intends to write more songs with powerful messages.

Her new album, Thank You, set to be released on May 13, will reveal the details of what Megan Trainor is all about next.

(WATCH the video below)

We're All About That SHARING… Click.