A directional drilling system comprises a driveshaft to couple to a drill string or a drill bit and an apparatus. The apparatus comprises an eccentric coupler disposed at the driveshaft and a coil coupled at one end to the eccentric coupler. In some embodiments, the coil comprises a fixed end and a rotating end. In response to a first transition temperature, the rotating end of the coil causes the eccentric coupler to rotate about the driveshaft, so as to move the driveshaft from a first orientation to a second orientation. Additional apparatus, methods, and systems are disclosed.