Instead of the instant gutteral realization that something we’ve just done is bad and has caused our bodies harm, we’d have to use logic to understand that even though the thing feels good, we have to stop or we’ll injure ourselves. This would mean that many people would choose instant gratification over long-term health and would injure themselves purposefully. We’d also have a lot more accidental death and permanent injury among teenagers especially. Realistically the human race would probably have gone extinct a long time ago.
Those of us with chronic illnesses would have a lot less suffering in our lives, although we’d probably still want cures due to other unpleasant symptoms like fatigue and because we don’t want long-term damage happening to our bodies and shortening our lifespans.
There actually have been cases in the real world of people having orgasms for no reason, some so frequently that they disrupt people’s lives. I guess all chronic pain patients would now be in this camp. They’d have to deal with people making obnoxious jokes like “gee I wish I had your condition, wink wink.”
We’d begin to make the connection that pleasure == something bad happening to our bodies, and might even stop enjoying pleasure due to that association. We’d find it harder to enjoy sex because we wouldn’t be sure whether we were getting pleased or getting injured.
A lot of conditions that are painful but don’t tend to cause any significant damage to the body, such as kidney stones, would no longer be problems.
Overall my own life would be a lot less difficult, but probably more confusing.