Personally; keep the cardio and do it every other day like you do right now. While your at it, on the days you don't run build functional muscle by doing push-ups and the like; (manual labor is good too). your diet is important too, Chicken, spinach, and fish are great... eat 5 or 6 medium sized meals a day; in my case: Breakfast, Lunch, one meal at around 2:15, dinner, and one about an hour before bed. Your body builds muscle at night, if you feed it.
the cardio keeps your heart in good shape, with all that eating you need it. Finally, agility training is great... try running a mile worth of 40 yard sprints every so often, It works muscle differently than distance running.