You can control the side effects you may get from a medication you take? If you get an infection you are taking meds. If you get kidney stones, you are very likely getting meds, if you injure yourself and need surgery you are getting meds. These carry risks, therefore, every time your chances of "perfect health" are decreasing.

I get that most people on HN, can control the air they breath as they have the means to decide where they want to live, this isn't the case for most of the people.

Cancer is literally just a numbers game, people in perfect health at their PEAK get diagnosed with cancer. A top club soccer player is now going through testicular cancer treatment.

I am not sure how general person can control any of this.