If you're a runner who doesn't strength train, then the question isn't if, but when you will be sidelined due to injury.
I used to look at cross training as an occasional activity. But, I started working out on a regular basis in May and have noticed a change in my pace and endurance. Now, I encourage all my runners to cross train. I've recently started strength training with weights more than body weighted exercises and I'm really enjoying it.
Here's what I plan to try tonight after my run: