"I am telling my story," she says. "People don't understand looking into the mirror and nothing seems right, putting on clothes that you really don't identify with. This is about getting to be who you really are."
Jenner promises she'll "talk about everything" in the eight-part E! series. "We're going to do a lot of fun things for the first time," she says. "We're going to go shopping for the first time. Maybe even some boy stuff, like ride a motorcycle, because girls do that too."
But more importantly, Jenner says, "We're going to do some good."
The new trailer comes shortly after President Barack Obama's historic shout-out to Jenner during Logo's Trailblazer Honors on Thursday. In a video message, Obama reflected on how far the country has progressed in 10 years. "All you have to do is look at this month's cover of Vanity Fair to see how America is more accepting of people for who they truly are," the president declared.
I Am Cait premieres Sunday, July 26 at 8/7c on E!.