An inertial navigation system includes a housing mountable to a vehicle and a sensor assembly located within the housing. The sensor assembly includes at least one accelerometer or gyroscope operable to measure an amount of movement of the sensor assembly. In addition, at least one adjustable mount attaches the sensor assembly to the housing and is adjustable to change its stiffness, and thus its natural frequency, based on a signal initially generated by the sensor assembly, processed by a processor, and then received through a feedback control loop. In one embodiment, the adjustable mount may take the form of a piezoelectric device. In another embodiment, the adjustable mount may take the form of a magnetorheological fluid device.