Step 11: Don’t Sweat a Few Aches
Soreness in your calves or hamstrings can be expected during training. It shows that your muscles are changing and getting stronger. But sharp pain in a joint -- your knee, hip, or ankle -- means you should lay off a few days, and see a doctor if it doesn’t get better.
You can prevent injuries, too: Warm up by walking a few blocks or doing jumping jacks. After you're done running, walk a little more, and then do gentle stretches, for up to 30 seconds each.