A method for altering the shape of an exhaust mixing structure extending from a downstream end of a jet engine nacelle nozzle. The method may involve attaching a first end of at least one actuator to the nacelle nozzle, and attaching a second end of the actuator to an inner skin of the exhaust mixing structure. At least one shape memory alloy (SMA) tendon connected to the actuator first and second ends may be activated such that the SMA tendon longitudinally constricts to move the inner skin of the exhaust mixing structure slidably along a longitudinal path. This causes a portion of the exhaust mixing structure to be flexed into a path of flow exiting the nacelle nozzle.