Worry increases pain. Just imagine the difference in how you experience a stomachache if you:
1. Have been told you might have stomach cancer and you're waiting for test results.
2. If you know it's because you have eaten too much ice cream.
Same stomachache, very different situation.
I read about a study where doctors induced stomachache in test subjects, by inflating a plastic tube in the gut. Separated into two groups, patients in one group were told "No problem, this is normal, you should be feeling better soon." and the other group were told things like "Oh. That does look strange. I don't know what that could be." Patients in the second group reported much stronger levels of pain than in the first group, under the exact same circumstances. That may be because negative emotions strongly increase pain perception.
Incessant worry drags us down, feeds negative emotions and thus fuels pain. We have a choice to do something about it. Resolving worries doesn't mean we need to fix our lives and make them perfect and worry-free, rather we need to change the way we think.
I recommend this book by dr. Marty Rossman, The Worry Solution. A pioneer in mind-body medicine, he has some good techniques on just how to overcome worry-thinking.