A 5K is a 3.12 mile race, and it's one of the most popular distances around the world for hobby joggers and elite athletes alike. Unlike a half marathon or full marathon, the 5K leaves you feeling tired, but able to actually walk afterwards — and with the same sense of accomplishment. Some seasoned runners may look down on the 5K, but I'm here to tell you that it's no small feat. In fact, in my 14 years of competitive running, the 5K was my main focus for 12 years. If you're looking to run y...