As amazing as it may seem, people (even some Physicians, unfortunately) STILL continue to claim that “running is bad for your knees.”  Please note – this is FALSE.  A peer-reviewed, long-term research and epidemiological study out of Stanford Medical School found that after 20 years, the knees of distance runners were actually HEALTHIER than those of a control group.  And a 2011 study by the American College of Sports Medicine concluded that “physical activity [including running] is BENEFICIAL, rather than detrimental, to join health” (here’s the study if interested:  http://www.npr.org/assets/news/2011/03/28/effect-of-physical-activity-on-knees.pdf).  The only exception to that is if you already have an injured knee, then running on it without correcting the cause could result in further injury, of course.