A seat assembly includes a seat frame, a sub frame, an electric motor, a transmission, and a flexible drive shaft. The seat frame includes a front support portion and supports a bottom cushion. The sub frame has a top plate and a base plate. The top plate supports a front cushion and rotatably supports a screw gear. The electric motor includes a first output member and is fixedly mounted to the front support portion of the seat frame. The transmission includes an input member and a second output member. The transmission is fixedly mounted to the base plate of the sub frame. The second output member of the transmission is drivingly connected to the screw gear of the sub frame. The flexible drive shaft is drivingly connecting the first output member of the electric motor to the input member of the transmission.