What started off as a friendship between two musical theater lovers has turned into a cosmetics businessworth millions.

Mented Cosmetics co-founders KJ Miller and Amanda Johnson became fast friends after meeting while performing a student-run musical at Harvard Business School.

"I was an actor in the show ... Amanda was running costumes backstage," Miller, 31, told Good Morning America while taking a break from the panels and fireside chats at Blavity's Summit 21 conference, which is dedicated to empowering women entrepreneurs and was held last weekend in Atlanta.