A treadmill may include two separate left and right belts rotating around two sets of rollers, four legs having an adjustable height via air suspension to customize an inclination of the treadmill, a thermoelectric assembly, a fragrance assembly having a rotating fragrance cartridge to emit various smells toward a user of the treadmill, a display on which exercise programs are played, and an attachment module having a dispensing tray on which treats are dispensed. A handle of the treadmill may have a sensor to sense a height and front-rear position, and a belt divider provided between the left and right belts may have position or proximity sensors to sense a left-right position. An inclination of the treadmill may be automatically adjusted according to positions detected by the sensors, and the fragrance assembly, attachment module, and inclination may be automatically operated in accordance with an exercise program played on the display.