Good Morning America co-host Robin Roberts is bald, thanks to breast cancer and chemotherapy. She's done a bang-up job of covering up since she shaved her head in preparation of the big fallout -- her wig is a perfect match for the hair that once sprouted from her scalp -- but she recently decided to bare her shiny scalp. She did it to challenge her comfort zone, she says.

What started as a dare had Roberts braving the catwalk the other day as part of Isaac Mizrahi's runway show, live from New York Fashion Week. All of her friends and fans knew she was doing the show -- they just didn't know she'd do it bald.

"This is who I am," Roberts said about her decision to ditch the wig.

When Roberts was diagnosed with breast cancer last July, the last thing she felt was beautiful. When the folks at Good Morning America dared her to be model, she seized the opportunity. It was a perfect way to push herself outside a certain comfort zone.

To transform herself into a supermodel, Roberts worked with Tyra Banks on walking the runway, Mizrahi on finding the perfect gown, and model Nikki Taylor on photo shoots -- a special layout will appear in an upcoming Redbook magazine.

Check out Roberts here in this video where you'll see a courageous woman make a bold statement as she fights to regain her health. Now that's what I call a model -- a role model.