I am looking to possibly run my first 5k this spring. It's actually in May and I wondered what I should do for training? Last summer, I was running 4+ miles. I just strarted up again recently, although not doing 4+ miles. I have been doing about half that. I got on the treadmill today and, since I don't know how fast I go, I just put the speed at a comfortable pace and it was 5.5 at an incline of at least 5. What should I work on? Speed? Stamina?