Complex sentence: She says she wanted to become a racer her whole life because of him, and was the fastest kid in tow growing up, but when she got to her first race, she saw all the other cars looking bigger, stronger and more confident.
Split into simpler sentences: She says she wanted to become a racer her whole life because of him. And then, when she got to her first race, she saw all the other cars looking bigger, stronger and more confident.