Personally, I believe the key to good health and fitness lies in moderation. Running isn't bad for most folks as long as it doesn't become an obsession. The same is true for bodybuilding, and most other athletic endeavors. I don't run much anymore, fast walking, bicycling, stair-stepping and swimming are what I enjoy doing for the cardio benefits. I switch these out each day that I do cardio, which is 5 or 6 days a week.
I know people who trained for ran marathons and who are now a bit crippled as a result of the beating their joints took from this endeavor. So instead of being more fit than the average person their age, they are less so. Despite that most twenty-somethings can't imagine themselves ever being sixty-something (like I am) most will live that long and longer. And you can trust me on this, regardless of how old one lives to be, life is better when you are fit and still able to be active and do the things you've always did. There are fit men in their 70's who work out at the gym I do. A couple of them were amateur bodybuilders and power lifters. They may not be as muscular or as cut as they once were, but they are much more fit than some folks in their thirties.
