Getting used to things makes two differences. The thing changes (you no longer enjoy the ice-cream as before. Even your bodily reaction to the sugar is weaker), and perceptual (you no longer notice it consciously, even though the basic thing stays unchanged).
Walking in Zurich i see people without gloves in the freezing cold. They are used to the cold. I am wondering whether they are actually not suffering from it, or they are just used to the suffering.
Clearly adaptation reduces the general bodily response to the cold. Hotter country citizens exposed to zurich freeze will suffer in their whole body and mind, a fate saved from the Swiss. Yet some of the suffering may stay with the Swiss where their adaptation is merely a case of being used to a drag. In this case, adaptation makes people unaware to an existing aversive state. (sometimes with the childish glory of "i can stand it" what glory is it to suffer in stupidity?!)
Ankther,point some adaptation means giving up rather than not having pain. Sometimes it is entirely irrational (called learned helplessness)