It's low-tech, but I use a Pampered Chef kitchen timer for pacing! It clips to my waistband or running belt, or I just hold it in one hand (it's light). I set the timer to one minute, start each minute with the running portion, then walk until it beeps again...push a button and start all over. There's a second setting that counts up at the same time I am doing intervals, so when I do a distance day I can see how long it takes me overall. I also use it to keep track of the 30 mins during the week.