"Why did I decide to do a series?" An emotional Caitlyn Jenner asks in a new clip from her upcoming docu-series, I Am Cait. "I am telling my story...People don't understand looking into the mirror and nothing seems right," she explains.

Jenner adds, "This is about getting to be who you really are."

Elsewhere in the trailer, Jenner takes a more lighthearted tone, teasing, "We're going to do a lot of fun things for the first time. We're going to go shopping for the first time. Maybe even some boy stuff, like ride a motorcycle — because girls do that too!"

In the clip, Jenner also bonds with her daughter Kylie and promises,"it's going to be quite a journey—we're going to do some good."

I am Cait debuts July 26 on E!