A hard disk drive has a disk, a spindle motor for rotating the disk, a head stack assembly including a swing arm and a head slider disposed at a leading end of the swing arm, and a controller operatively connected to the head slider. The head slider is positioned by the swing arm over the disk and floats in such position during a read/write operation in which data is being read from or written onto the disk. The head slider has a head slider body, a magnetic head embedded in the body, and at least one resistive heating element that generates heat when current is supplied thereto. The heat causes the body of the head slider to thermally expand in such a way that the profile of the disk-facing side of the body of the head slider changes. The controller controls the height of the head slider relative to the disk by controlling the supplying of current to the resistive heating element(s). First, the controller measures the distance between the head slider and the disk during a read/write operation, and compares the measured distance with a predetermined optimum distance or allowable range of distances. Current is supplied and/or cut off from the resistive heating element(s) when the measured distance is different from the predetermined optimum distance or is outside the predetermined range of distances.