Since recently finishing competing collegiality, I plan to continue a full training regime over the next couple of years to bring down my 5k/10k PRs and eventually moving up to the marathon. Over the past year I've noticed that my body is becoming more sensitive to injury, especially in the knees. I've also found that I occasionally start to have pain in my knees when doing activities like hiking and skiing, where as these sorts of things had previously never happened.
For some of you older guys out there, I am curious what the long term effects of running have been on you? If you answer, please share your mileage numbers for reference.