Ok I read this web site everyday for about 10 years but don't contribute too much. now its time for a bit of advice. I used run the 400/800/1500 years ago. Standard of about 48, 1.50, 3.47... nothing amazing but not bad at all.. have been off a few years but now im back running a nice bit... back running like a 5km/10km guy... ran one 5km in like 17min in a park, won, but it felt hard. I want to improve, think I can still roll over 3km/5km.. what is a the key to running fast over that distance? tempos? hills? miles? all of the above? what about some good workouts? any help would be good.