Human beings live their lives largely in their minds. Your mind constructs an image of reality. The rest of you then works to build, maintain or change that reality. This reality can be objective – for example this tree exists. It could be subjective – for example I like ice cream. However, there could be a third reality one that is intersubjective. This is truth because more than one person believes it. For example, the dollar has value. This statement is only true because you and I both believe it to be so. The minute either of us stopped believing, it would no longer be so.
Intersubjective realities have been created by mankind for a while. God exists. In the absence of proof, the only reason we believe is because people around us seem to do so. The scriptures say it is so. Prophets have spoken about it. Wise men have studied it and undoubtedly know better. It does not take a whole lot for us to believe in intersubjective reality. In fact, we are so inclined. Battering rams are used to subjugate those who don’t. Armies are deployed to make people believe in the power of the dollar. From such practices, urban legends are born. One that you believe in just because it sounds true.
Running is bad for you. There is really no evidence for this. A study of 75,000 people in 2013, one of the largest ever conducted, showed that runners did not have a pre-disposition toward arthritis, or a bad knee. Of course if you already had a problem, this could be aggravated. Poor practices, running on very hard surfaces for example could easily cause an injury. This would however hold true for almost anything you did. However, the urban legend persists. Modern technology has brought bucketloads of information. However, it has also made the spreading of legends more efficient. Be careful what you believe.