I quit "distance" running in 2000 when medical tests at an anti-aging clinic showed that I was not recovering from my hard training efforts and that over time, it would age me faster than a more moderate approach to running. I still do occasional social long runs, but I seldom run for more than six miles. I only race the 400/800 at the national level. However, I lift HARD 3-5 days/week. I'm 74. Here's a photo of me taken earlier this year. Running will keep your heart healthy. Lifting and great nutrition can keep the rest of your body healthy. (I'll probably delete this photo in a few days, but this is what an older healthy runner can look like.)