ok so there is this trick that ive heard be called by about 8 different names among them "the flame and the void"
"the oneness" and "image centering". basically you visualize a flame [i spose something else could work but thats what works for me] surronded by nothingness and feed all of your feeling and emotion and other things that cloud up your mind into it and once you master this it not only makes you impervious to cold, it also heightens your reaction times and sensory perception.