I considered taking up running for excercise about ten years ago, but opted for biking instead. I was always a bit worried about all that force/trauma to the knees, from running. Having a few relatives with knee troubles as they got older, I wanted to avoid that scenario.
The problem with biking is that if you are really pushing hard and are tired, you become accident prone.
I had a really bad wreck (hit a bump in the road and went sailing through the air). Broke three ribs and punctured a lung (5 days in hospital).
I hung up my bike and started forefoot strike running. Forefoot strike (or natural or barefoot style) running is pretty much injury free once you get used to it. That said, it takes a long time to get used to it.
Natural running prevents all the banging of the knees and feet and uses leverage and muscle instead. Check it out.