How Do You Decide Which Exercise Works for You?

I thought about this as I read Mark Rippetoe's fascinating discussion of why running is not the panacea that so many people think it is:

This highly informative discussion is intended for those people who have taken seriously the advice of doctors, physical therapists, exercise physiologists, and the popular media’s dutiful reporting on these sources of common misinformation about what kind of physical activity is best for your long-term health and continued ability to participate in the business of living well.

Rippetoe goes on to make the case against running and for strength training. Okay, fair enough. I get that we need to be strong, especially as we get older; and strength training helps with this. But I can't help but feel that a balanced approach is also good if you want to address Rippetoe's concern that "the more you run, the better you are at running and the worse you are at being strong."

I have a number of training goals and they change all the time. For example, right now, I want to run a 13 minute mile which I know is not good, but is about the best I can do. It's important to me. Why? Because running is a skill that can help in situations such as running fast away from something or someone, or running to catch a subway or bus, or running after a kid or adult who needs help etc.

Do I need to run long slow distance? No, probably not. I also want to know self-defense because it is important to me and I would like to take more Krav Maga lessons. I suppose these goals take away from strength building but I don't have time for all of it. So what do you focus on? If being good at strength building builds strength, that's good, but will it help me to run faster or be better at self-defense? Wouldn't practice of these "sports" or exercise be the most helpful? Or maybe a balanced approach that focused on strength and practicing running and Krav Maga would be best. If we only strength train, is that enough or does it depend on one's goals?