I bought a gps: the Garmin Forerunner 305. This decision was borne out of a desire to get a grip on both my pace and my heart rate. The two are no doubt linked and are probably good metrics of how close I am to blowing up my innards.
Todays run was 10.24 km at an average pace of 5.00 min/km (12 km/h) for a total time of 51:13. My route is shown below!
And now my heart rate vs distance. My speed is also shown. As is a bit evident, I finished with an uphill push.
This device has many features for pre-programming a “workout”. My next step is to set it to alarm if I vary my pace too far from a target and also alarm if my heart rate rises too high. Maybe next time I will include a photo of my sweaty sexy chest with the heart rate monitor attached…
Eat Logical Sentences 
They’re awesome! My sister and her hubby have one…actually, they’ve had a couple, but one blitzed out. Unfortunately I do not get to receive the benefits of this anymore as I don’t live nearby, and will have to do things the old fashioned way…choose a location with approximate kilometres and run that. I’m not thinking it a sound financial choice right now to do so. Sounds like you’re doing very well. Not surprisingly. Keep it up sir!
I mean for me to purchase a garmen, not choosing a location to run.