There is a common misconception among people who run; they often think that their workouts can be limited to running. This is unfortunate since strength training helps to build lean muscle mass, and it can actually help your running. The perfect leg strengthening exercise for running is the walking lunge.
Walking lunges emphasize the propulsion phase of running, aka forward motion. Isn't that what running is all about, moving your body forward through space? Not only that, but aside from strengthening (and toning) your glutes, walking lunges can help increase your stride length, which ultimately will help increase your speed, and who doesn't want to run faster?
If you run, I highly encourage you to add some walking lunges to your fitness routine. I would start with two sets of 10 lunges per leg. You can add hand weights to increase the work. Or to challenge your sense of balance, try holding a physio ball over your head while taking your lunges for a walk.
If you need to review this wonderful exercise, check out Back to Basics: Walking Forward Lunge.
Fit's Tip: Walking lunges are also a great conditioning exercise for downhill skiing, telemarking, and cross country. Yes, I think the everyone in the world could benefit from walking lunges!