Simple question: Can you do a one-legged squat? If you think of running as a series of one-legged hops, then you should be able to squat on one leg. Why? For the simple reason that you’re going to land on one leg after taking off in the air from the other leg, i.e. you’re basically hopping from one leg to another when you run, and if you can not handle your body weight on one leg, then you probably need to go back and do some remedial strength work before you consider running a bunch of miles.
There are a number of functional screens out there – Grey Cook’s work and Gary Gray’s work come to mind – that can help an athlete figure out where they are weak, where they are asymmetric, and where they have a higher probability of injury. But even if you can’t find someone to do the screen, why wouldn’t you start working on functional strength right away? The Lunge Matrix that I use (which is rooted in Gary Gray’s work) is a great warm-up because it’s getting the body to move in all three planes of motion before a run – which is primarily a sagittal plane activity, with a little bit of transverse plane (hips and shoulders oscillating throughout the gait). The second thing you should consider is Active Isolated Flexibility (AIF) as a daily practice after your run. I’ve seen dozens of runners do this work and stay injury free. With AIF, you gain flexibility, but you also gain strength, and it’s a great way to improve your body’s symmetry.
The bottom line is that staying healthy requires work, but not a tremendous amount. Functional Strength can help you stay healthy, staying healthy leads to consistency, and consistency leads to a faster runner.