I am a runner training for my junior HS track season. I ran 16:39 for the 5k this XC season, but I am hoping to have a breakout track season this spring. I run against a lot of people who can only run either the 800 and the 1500 or the 1500 and the 3000. I'd say that my priority is the 800 and 1500, but I still would like to be able to run a solid 3000. What should I incorporate into my training to try and maintain solid ability across all three of these distances?