Help for 800 meters/ mid distance?

Keep up the long distance workouts because you need to build up lung capacity. Anything that gets you breathing hard is good for this. You need that extra endurance at the end of a race you have more in you then your opponents. Also, keep in mind that when your times aren't improving when you are running by yourself, they will be better in a race when you have adrenaline and people to push you harder.