Have you ever taken a cold shower on a cold day?
It was not intentional. You were not aware that the heater had broken down. You had massaged all the shampoo into your hair, and soaped yourself from your head to toe. Then you turned on the shower and the water came pouring down in torrents.
You stuck your hand out to intercept the downpour. The water ran through your fingers, sending a chilling sensation to your spine. You waited for the hot water to come on, but the falling stream remains too cold for comfort. You held your hand in front of the nozzle and anticipated for a change of temperature. Somehow after a while, your mind was tricked into thinking that the water had become warmer when it was your palm that became desensitized to the cold.
You dip toes into the shower, followed by your thighs. It was tolerable. Then you took a step closer, and the icy waters landed on your torso, making a run down your chest and your tummy before passing down your legs. You felt your body trembling, your muscles shivering under your skin. Then you struck up more courage, and moved your head under the shower. Your brain just froze for the next few seconds.
In your mind, you told yourself to get it over and done as quick as you can. Gathering much will power, you turned the flow to the maximum. Vigorously, you rubbed the soap off your skin.
Just when your skin started to feel clean and clear, you noticed a change in the temperature. Gradually, the water became warmer, and warmer. Then you saw some fog forming on the mirror beside you. Steam rose to the ceiling and out of the cubicle. It was getting hot.
By then, you did not need the heater anymore. Your body had already accustomed itself to the cold water, your skin had desensitized to the adversive stimulus. And the warmth - it no longer mattered.