Mary-Kate Olsen brought a friend along yesterday to a yoga class in NYC. She's on the East Coast again after her recent trip to Greece, where she relaxed during an art-themed vacation with her boyfriend Nate Lowman. MK and Ashley are now gearing up for Spring Fashion Week, which kicks off early next month. The sisters also signed on to participate in the first ever Fashion's Night Out, where they will be bartending at Barneys to benefit charity.