"First, what did not happen: I didn’t develop any knee, foot, back, or hip pains. I don’t feel exhausted at the end of the day or week. My productivity and abil

"First, what did not happen: I didn’t develop any knee, foot, back, or hip pains. I don’t feel exhausted at the end of the day or week. My productivity and ability to concentrate did not go down." Am I misunderstanding the double negatives here? Are these things that DID happen?