You may want to find a 1/2 marathon training plan and stick to it. It would include a weekly long run that ramps you up along with shorter weekly runs. If you do a lot of EQ and/or EPO have blood work done to make sure your crit doesn't get too high or you won't make it to the event. Don't take Anavar, just trust me on that. I'd take two parts deca or EQ to one part test. Go too high on the test and you will leave yourself open to tendon/ligament and other injuries. Training for 10 mile is hard on your connective tissues so I wouldn't run every day if I were you. You can't take a pill for endurance. It's just something that takes time to build toward. Make sure your nutrition is good as well. Try carbo loading with ABB carbo force the 2 days prior and bring 4-7 GU packs with you. Cycling, spinning, swimming will also help you get your VO2 max where you need to be. Cross training helps because you won't be able to just run enough without exposing yourself to injury. Oh, and let me know how that beetroot stuff works.

Damn man beetroot juice!?! I had a link opened in 2 seconds flat after reading that. Looks like there are the obvious "nicely packaged for advertising and taste," crap but anybody know of a good source for it?
Oh and as far as cardio and gear I use speed stack an it does wonders.

Beetroot juice, 500ml and gargle each mouthful then swallow, don't clean out your mouth or drink anything else for an hour after.

Effects last 24 hours, it drops your blood pressure and increases oxygen carrying capacity of blood.

Get pure juice not the stuff that they mix with apple juice etc.

Starts working after 3-4 hours, prepare to be amazed it's like EPO but legal.

Anavar is good for cardio, test and deca not so good.