How to Increase Stamina?

[shotzz]

Hi guys,
I'm 14 years old, 5"6 or 5"7, 125 lbs(57kg) and I need to increase my stamina. I am aiming specifically for the 400-1500m events. The last time i ran a cross country was about 3 years ago. I was one of the top runners in my district, however since then I have moved country and I feel I have lost a great deal of fitness. Diet wise, I eat anything I want(I have a high metabolism), I don't care about nutritional value as such, I eat fast food about once every three months. My 400m timings are unknown since I have no proper track. I need some routines or training methods I can use to increase my stamina, that I could do on a 3-4 day basis per week. I know I'm sounding a bit vague, but any sort of help would be appreciated.

Extra info-
My school sports day is Feb 2013 and my main competitors are rugby players.
In my grade, I have the second highest stamina(I want to be first)
There is a 50m x 50m car park which I can use as a track.
I sometimes run up and down a 12 storey building 5 times(1000 stairs), but I don't know if that would increase my stamina.

[Zacface]

Hi guys,
I'm 14 years old, 5"6 or 5"7, 125 lbs(57kg) and I need to increase my stamina. I am aiming specifically for the 400-1500m events. The last time i ran a cross country was about 3 years ago. I was one of the top runners in my district, however since then I have moved country and I feel I have lost a great deal of fitness. Diet wise, I eat anything I want(I have a high metabolism), I don't care about nutritional value as such, I eat fast food about once every three months. My 400m timings are unknown since I have no proper track. I need some routines or training methods I can use to increase my stamina, that I could do on a 3-4 day basis per week. I know I'm sounding a bit vague, but any sort of help would be appreciated.

Extra info-
My school sports day is Feb 2013 and my main competitors are rugby players.
In my grade, I have the second highest stamina(I want to be first)
There is a 50m x 50m car park which I can use as a track.
I sometimes run up and down a 12 storey building 5 times(1000 stairs), but I don't know if that would increase my stamina.

400-1500 isn't really even a stamina event, honestly. That is a sprint.

I would recommend doing a lot of interval work.
10x100m Sprints: 3x Week
1x5000m Hard Run: 2x Week

Even training for the 400 you can go out and run several 400s in a day. I mean, training for these distances is primarily going to be just putting in the speed work time. Your stamina for these types of events is almost non-related to super distance running. In fact, you don't want to spend much time (if any) doing pure distance work.

[shotzz]

400-1500 isn't really even a stamina event, honestly. That is a sprint.

I would recommend doing a lot of interval work.
10x100m Sprints: 3x Week
1x5000m Hard Run: 2x Week

Even training for the 400 you can go out and run several 400s in a day. I mean, training for these distances is primarily going to be just putting in the speed work time. Your stamina for these types of events is almost non-related to super distance running. In fact, you don't want to spend much time (if any) doing pure distance work.

Thanks!