After eating gluten, sugar, processed oils, and a bunch of crap most of my life, I think I just got de-sensitized to it. Both my body just putting up with it, and me putting up with all of the symptoms that went along with it -- digestive problems, skin conditions, wildly varying energy levels, inability to lose weight, etc.
Once I went Paleo, and realized that all of these things I had been putting up with were avoidable, I now think of them in my mind as problems I can correct, rather than just "part of life". Now, if I cheat and these symptoms come back, I have a totally different view of them.
I am also now a lot more sensitive to food "pollutants", especially sugar and gluten. Just one bite of these things sends me off into unhappy land. This was a feeling that I used to consider normal, but now know that it is not.
Going strict Paleo really redefined the baseline of what I consider to be good health.