A motor unit includes a motor shaft for receiving a motor provided driving force and an auxiliary shaft for receiving an externally provided driving force. A first torque transmission path transfers the externally provided driving force to a drive mechanism and a second torque transmission path transfers the motor provided driving force also to the drive mechanism. A first one way drive is provided in the first torque transmission path between the auxiliary shaft and the drive mechanism such that when the drive mechanism is being driven by the motor provided driving force through the second torque transmission path, the auxiliary shaft is able to freewheel. The motor unit can drive any apparatus where the externally provided driving force is provided by manually operable pedals fixed for rotation with the auxiliary shaft.