Our body generates a lot of heat during metabolic activities and other bodily functions. All this heat needs to be dissipated so as to keep the body temperature low. If the external temperature (outside of our body) is lower than the body's temperature, the body will loss the heat to the environment and be at a comfortable temperature. If, on the other hand, the external temperature is more than the body's temperature, then the body will actually gain it from the surroundings. In such a scenario, the body will have to depend on its moisture and water content to control its temperature (by losing the body's moisture content). Hence, we feel much more comfortable when the surrounding temperature (23 degrees celsius) is much lower than our body's internal temperature (37 degrees celsius).
Hope this helps.