Your achy knees while running may be due to weak hips. Strengthen the hips and running may be enjoyable again. not to mention, these exercises help shrink your hips! - I personally am not a runner, but I do happen to have very achy knees!
Drop a Jean Size Workout. "I did this workout 3 days a week last year and not only did I drop a jean size, but I kept it off. I highly recommend this workout and just about any workout that comes from Fitness Magazine. Their workouts are reliable.