Running is my weakest discipline because it's so hard on the joints. My coach recommended keeping a 90-strides-per-minute pace and maintaining it throughout a run. I use my swimmer's Sportcount (any stopwatch will do) and count out the number of times my right foot hits the ground in 30 sec intervals (and then double it). I measure my "cadence" every mile or so and know when to ease off or pick up the pace.
As I grew stronger running, I was found myself gradually getting faster, taking longer strides, lifting my knees up higher. My stride, however, always remained the same.