Take time to warm-up before you start your run. Just because he's standing at the end of the driveway looking back at you with a scowl on his face doesn't mean that you should risk pulling a muscle by not giving yourself the 5 to 10 minutes it takes to get ready for the stress and labor of running.
Oh, and don't forget to take it easy during the last mile of your run in order to cool-down. The longer and harder you run, the longer your cool-down period should take. It'll remove waste products from your muscles and help your body recover from the increased exertion.