There's plenty of exercise science stuff, much of it conflicting. Also, even if some damage to health from running were 100% certain, you need to get a handle

There's plenty of exercise science stuff, much of it conflicting. Also, even if some damage to health from running were 100% certain, you need to get a handle on just how likely and how dangerous the damage is. Is it analogous to exposure to a carcinogen that has a 95% chance of leading to cancer and death within 2 years? Or is it analogous to exposure to minor carcinogen that means you have, say, a 2% greater likelihood of developing cancer over the course of your life? For me, I see that I and all my running friends seem healthier and more vibrant than an average person of the same age. My heart is stronger, running improves bone density, (at least for me) improves strength and reduces pain in joints, improves my balance, helps keep me slim, etc. It gets me out every day, often into beautiful mountains with friends. For as long as I keep running I expect to reap these benefits. Would I stop or cut down if I were told, with certainty, that running would cause me to die, say, 2 years sooner than I would otherwise if I wasn't running? Not likely, it increases my quality of life in too many important ways. If that number were instead, say, 10 - 20 years, then yeah sure, I might cut down. But there is no science remotely resembling that. I don't think there's anything out there that establishes to any degree of confidence that lots of running reduces life expectancy at all.