If you're an avid runner, it's more than likely that someone has pulled you aside to warn against the possible effects it could have on your knees. While they aren't totally wrong in their warning, they aren't totally right either.
This video from SciShow provides an in depth look at exactly what running does to the human body (specifically to the knees) this way you can acknowledge, evaluate and weigh the risks all on your own.
So, there you have it! There's no real definitive proof to concur in one way or another, so like the video says take people's warnings with a grain of salt!
I however, couldn't just leave it that open-ended so I did a little bit more research outside of the video.
According to ACTIVE there are 6 key benefits to running—
Improve your overall health
Boost Your Confidence
Alright, those seem pretty beneficial, no? I do think some of them are bit redundant—i.e. the last three, but still, sounds like a pretty good deal.
Now for the negative side effects. According to LIVESTRONG these are the 4 most detrimental aspects of frequent running—
Hard on your heart
Make it harder to lose weight (increased appetite)
The conclusion I've drawn from both, although I'll let you draw your own, is that running, much like anything else, if done in moderation is a totally sustainable, healthy means of exercise capable of bettering your life. If you run from the time you wake up to the time you go to bed, that's another story entirely, but who the hell wants to do that?!